[Entity Analytics][Privmon] CSV upload (#221798)

## Summary
 
This PR adds the ability to upload a CSV file with privileged users from
the Entity Analytics pages

## Changes

### Backend

- Added (or completed) the upload CSV route:
`/api/entity_analytics/monitoring/users/_csv`
- Added shared utilities for batching with Node streams
- Added bulk processing actions for the upload
  - Parsing users from CSV
  - Soft delete for omitted users 
  - Batch upsert via the bulk API
- Added a check for installing all required privmon resources

### Frontend

- File uploader components
- File validation logic
- Updated EA privmon page to account for the new flow
- Added managing users panels 
  - open upload flow (same as asset criticality)

## Screen recording


https://github.com/user-attachments/assets/7956f1cf-49e0-4430-8c23-7d6178a15342

## How to test

#### Prerequisite

Make sure you have a CSV file with usernames
Check
[here](https://gist.github.com/tiansivive/0be2f09e1bb380fdde6609a131e929ed)
for a little helper script

Create a few copies where some of the users are deleted, in order to
test soft delete

1. Start up kibana and ES
2. Navigate to Security > Entity Analytics > Privilege User Monitoring
3. Select the `File` option to add data
4. Add one of the CSV files to the open modal and upload
5. Repeat but now upload one of files with the omitted users 

Alternatively, testing only the backend only is possible by directly
hitting the API wit curl
```
curl -u elastic:changeme \
  -X POST "http://localhost:5601/api/entity_analytics/monitoring/users/_csv" \
  -H "kbn-xsrf: true" \
  -F "file=@test.csv;type=text/csv"
```

#### Verifying

Easiest way is to use the dev tools to `_search` the privmon users index
with:
```
GET .entity_analytics.monitoring.users-default/_search
```

Look for number of hits and/or use `query` to search for omitted users. 


## Remaining work

- [x] API integration tests
- [ ] Batching logic unit tests
- [ ] E2E tests?

---------

Co-authored-by: machadoum <pablo.nevesmachado@elastic.co>
Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>

oas_docs/output/kibana.serverless.yaml

@@ -11146,58 +11146,48 @@ paths:
         - Security Entity Analytics API
   /api/entity_analytics/monitoring/users/_csv:
     post:
-      operationId: BulkUploadUsersCSV
+      operationId: PrivmonBulkUploadUsersCSV
       requestBody:
         content:
-          text/csv:
-            schema:
-              type: string
-        description: CSV file containing users to upsert
-        required: true
-      responses:
-        '200':
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  upserted_count:
-                    type: integer
-          description: Successful response
-      summary: Upsert multiple monitored users via CSV upload
-      tags:
-        - Security Entity Analytics API
-  /api/entity_analytics/monitoring/users/_json:
-    post:
-      operationId: BulkUploadUsersJSON
-      requestBody:
-        content:
-          text/json:
+          multipart/form-data:
             schema:
               type: object
               properties:
-                users:
-                  items:
-                    type: object
-                    properties:
-                      is_monitored:
-                        type: boolean
-                      user_name:
-                        type: string
-                  type: array
-        description: JSON file containing users to upsert
-        required: true
+                file:
+                  description: The CSV file to upload.
+                  format: binary
+                  type: string
+              required:
+                - file
       responses:
         '200':
           content:
             application/json:
               schema:
+                example:
+                  errors:
+                    - index: 1
+                      message: Invalid monitored field
+                      username: john.doe
+                  stats:
+                    failed: 1
+                    successful: 1
+                    total: 2
                 type: object
                 properties:
-                  upserted_count:
-                    type: integer
-          description: Successful response
-      summary: Upsert multiple monitored users via JSON upload
+                  errors:
+                    items:
+                      $ref: '#/components/schemas/Security_Entity_Analytics_API_PrivmonUserCsvUploadErrorItem'
+                    type: array
+                  stats:
+                    $ref: '#/components/schemas/Security_Entity_Analytics_API_PrivmonUserCsvUploadStats'
+                required:
+                  - errors
+                  - stats
+          description: Bulk upload successful
+        '413':
+          description: File too large
+      summary: Upsert multiple monitored users via CSV upload
       tags:
         - Security Entity Analytics API
   /api/entity_analytics/monitoring/users/{id}:
@@ -66988,6 +66978,34 @@ components:
       required:
         - type
         - status
+    Security_Entity_Analytics_API_PrivmonUserCsvUploadErrorItem:
+      type: object
+      properties:
+        index:
+          nullable: true
+          type: integer
+        message:
+          type: string
+        username:
+          nullable: true
+          type: string
+      required:
+        - message
+        - index
+        - username
+    Security_Entity_Analytics_API_PrivmonUserCsvUploadStats:
+      type: object
+      properties:
+        failed:
+          type: integer
+        successful:
+          type: integer
+        total:
+          type: integer
+      required:
+        - successful
+        - failed
+        - total
     Security_Entity_Analytics_API_RiskEngineScheduleNowErrorResponse:
       type: object
       properties:

oas_docs/output/kibana.yaml

@@ -13305,58 +13305,48 @@ paths:
         - Security Entity Analytics API
   /api/entity_analytics/monitoring/users/_csv:
     post:
-      operationId: BulkUploadUsersCSV
+      operationId: PrivmonBulkUploadUsersCSV
       requestBody:
         content:
-          text/csv:
-            schema:
-              type: string
-        description: CSV file containing users to upsert
-        required: true
-      responses:
-        '200':
-          content:
-            application/json:
-              schema:
-                type: object
-                properties:
-                  upserted_count:
-                    type: integer
-          description: Successful response
-      summary: Upsert multiple monitored users via CSV upload
-      tags:
-        - Security Entity Analytics API
-  /api/entity_analytics/monitoring/users/_json:
-    post:
-      operationId: BulkUploadUsersJSON
-      requestBody:
-        content:
-          text/json:
+          multipart/form-data:
             schema:
               type: object
               properties:
-                users:
-                  items:
-                    type: object
-                    properties:
-                      is_monitored:
-                        type: boolean
-                      user_name:
-                        type: string
-                  type: array
-        description: JSON file containing users to upsert
-        required: true
+                file:
+                  description: The CSV file to upload.
+                  format: binary
+                  type: string
+              required:
+                - file
       responses:
         '200':
           content:
             application/json:
               schema:
+                example:
+                  errors:
+                    - index: 1
+                      message: Invalid monitored field
+                      username: john.doe
+                  stats:
+                    failed: 1
+                    successful: 1
+                    total: 2
                 type: object
                 properties:
-                  upserted_count:
-                    type: integer
-          description: Successful response
-      summary: Upsert multiple monitored users via JSON upload
+                  errors:
+                    items:
+                      $ref: '#/components/schemas/Security_Entity_Analytics_API_PrivmonUserCsvUploadErrorItem'
+                    type: array
+                  stats:
+                    $ref: '#/components/schemas/Security_Entity_Analytics_API_PrivmonUserCsvUploadStats'
+                required:
+                  - errors
+                  - stats
+          description: Bulk upload successful
+        '413':
+          description: File too large
+      summary: Upsert multiple monitored users via CSV upload
       tags:
         - Security Entity Analytics API
   /api/entity_analytics/monitoring/users/{id}:
@@ -76488,6 +76478,34 @@ components:
       required:
         - type
         - status
+    Security_Entity_Analytics_API_PrivmonUserCsvUploadErrorItem:
+      type: object
+      properties:
+        index:
+          nullable: true
+          type: integer
+        message:
+          type: string
+        username:
+          nullable: true
+          type: string
+      required:
+        - message
+        - index
+        - username
+    Security_Entity_Analytics_API_PrivmonUserCsvUploadStats:
+      type: object
+      properties:
+        failed:
+          type: integer
+        successful:
+          type: integer
+        total:
+          type: integer
+      required:
+        - successful
+        - failed
+        - total
     Security_Entity_Analytics_API_RiskEngineScheduleNowErrorResponse:
       type: object
       properties: