[OSQuery Plugin] Migrate usage og authc.getCurrentUser to coreContext.security (#187014)

Part of https://github.com/elastic/kibana/issues/186574

## Summary

This PR migrates the OSQuery Plugin's route handlers that consume
`authc.getCurrentUser` to use coreContext.security

Background: This PR serves as an example of a plugin migrating away from
depending on the Security plugin, which is a high priority effort for
the last release before 9.0.

### Checklist

Delete any items that are not applicable to this PR.

- [ ] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

x-pack/plugins/osquery/server/routes/asset/update_assets_route.ts

@@ -42,9 +42,10 @@ export const updateAssetsRoute = (router: IRouter, osqueryContext: OsqueryAppCon
           },
         },
       },
-      async (context, request, response) => {
-        const savedObjectsClient = (await context.core).savedObjects.client;
-        const currentUser = await osqueryContext.security.authc.getCurrentUser(request)?.username;
+      async (context, _request, response) => {
+        const coreContext = await context.core;
+        const savedObjectsClient = coreContext.savedObjects.client;
+        const currentUser = coreContext.security.authc.getCurrentUser()?.username;
 
         let installation;
 

x-pack/plugins/osquery/server/routes/live_query/create_live_query_route.ts

@@ -42,7 +42,8 @@ export const createLiveQueryRoute = (router: IRouter, osqueryContext: OsqueryApp
       },
       async (context, request, response) => {
         const [coreStartServices] = await osqueryContext.getStartServices();
-        const soClient = (await context.core).savedObjects.client;
+        const coreContext = await context.core;
+        const soClient = coreContext.savedObjects.client;
 
         const {
           osquery: { writeLiveQueries, runSavedQueries },
@@ -106,7 +107,7 @@ export const createLiveQueryRoute = (router: IRouter, osqueryContext: OsqueryApp
         }
 
         try {
-          const currentUser = await osqueryContext.security.authc.getCurrentUser(request)?.username;
+          const currentUser = coreContext.security.authc.getCurrentUser()?.username;
           const { response: osqueryAction, fleetActionsCount } = await createActionHandler(
             osqueryContext,
             request.body,

x-pack/plugins/osquery/server/routes/pack/create_pack_route.ts

@@ -64,7 +64,7 @@ export const createPackRoute = (router: IRouter, osqueryContext: OsqueryAppConte
         const agentPolicyService = osqueryContext.service.getAgentPolicyService();
 
         const packagePolicyService = osqueryContext.service.getPackagePolicyService();
-        const currentUser = await osqueryContext.security.authc.getCurrentUser(request)?.username;
+        const currentUser = coreContext.security.authc.getCurrentUser()?.username;
 
         // eslint-disable-next-line @typescript-eslint/naming-convention
         const { name, description, queries, enabled, policy_ids, shards = {} } = request.body;

x-pack/plugins/osquery/server/routes/pack/update_pack_route.ts

@@ -71,7 +71,7 @@ export const updatePackRoute = (router: IRouter, osqueryContext: OsqueryAppConte
         );
         const agentPolicyService = osqueryContext.service.getAgentPolicyService();
         const packagePolicyService = osqueryContext.service.getPackagePolicyService();
-        const currentUser = await osqueryContext.security.authc.getCurrentUser(request)?.username;
+        const currentUser = coreContext.security.authc.getCurrentUser()?.username;
 
         // eslint-disable-next-line @typescript-eslint/naming-convention
         const { name, description, queries, enabled, policy_ids, shards = {} } = request.body;

x-pack/plugins/osquery/server/routes/saved_query/create_saved_query_route.ts

@@ -55,7 +55,7 @@ export const createSavedQueryRoute = (router: IRouter, osqueryContext: OsqueryAp
           ecs_mapping,
         } = request.body;
 
-        const currentUser = await osqueryContext.security.authc.getCurrentUser(request)?.username;
+        const currentUser = coreContext.security.authc.getCurrentUser()?.username;
 
         const conflictingEntries = await savedObjectsClient.find<SavedQuerySavedObject>({
           type: savedQuerySavedObjectType,

x-pack/plugins/osquery/server/routes/saved_query/update_saved_query_route.ts

@@ -51,7 +51,7 @@ export const updateSavedQueryRoute = (router: IRouter, osqueryContext: OsqueryAp
       async (context, request, response) => {
         const coreContext = await context.core;
         const savedObjectsClient = coreContext.savedObjects.client;
-        const currentUser = await osqueryContext.security.authc.getCurrentUser(request)?.username;
+        const currentUser = coreContext.security.authc.getCurrentUser()?.username;
 
         const {
           id,