[Fleet] Add 'No Tags' filter to agent table (#216944)

## Summary

Closes #213933 

Adds a `No Tags` filter to the filter select on the agents table so that
users can filter for agents without tags.


https://github.com/user-attachments/assets/1223d049-1f21-4565-854c-75776ae4609b



### Checklist

Check the PR satisfies following conditions. 

Reviewers should verify this PR satisfies this list as well.

- [ ] Any text added follows [EUI's writing
guidelines](https://elastic.github.io/eui/#/guidelines/writing), uses
sentence case text and includes [i18n
support](https://github.com/elastic/kibana/blob/main/src/platform/packages/shared/kbn-i18n/README.md)
- [ ]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [ ] [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
- [ ] If a plugin configuration key changed, check if it needs to be
allowlisted in the cloud and added to the [docker
list](https://github.com/elastic/kibana/blob/main/src/dev/build/tasks/os_packages/docker_generator/resources/base/bin/kibana-docker)
- [ ] This was checked for breaking HTTP API changes, and any breaking
changes have been approved by the breaking-change committee. The
`release_note:breaking` label should be applied in these situations.
- [ ] [Flaky Test
Runner](https://ci-stats.kibana.dev/trigger_flaky_test_runner/1) was
used on any tests changed
- [ ] The PR description includes the appropriate Release Notes section,
and the correct `release_note:*` label is applied per the
[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

### Identify risks

N/A

x-pack/platform/plugins/shared/fleet/public/applications/fleet/sections/agents/agent_list_page/hooks/use_fetch_agents_data.tsx

@@ -32,7 +32,9 @@ import { getKuery } from '../utils/get_kuery';
 
 const REFRESH_INTERVAL_MS = 30000;
 const MAX_AGENT_ACTIONS = 100;
-
+const NO_TAGS_VALUE = i18n.translate('xpack.fleet.noTagsValue', {
+  defaultMessage: 'No Tags',
+});
 /** Allow to fetch full agent policy using a cache */
 function useFullAgentPolicyFetcher() {
   const authz = useAuthz();
@@ -287,7 +289,7 @@ export function useFetchAgentsData() {
 
           setAgentsStatus(agentStatusesToSummary(statusSummary));
 
-          const newAllTags = agentTagsResponse.data.items;
+          const newAllTags = [...agentTagsResponse.data.items, NO_TAGS_VALUE];
           // We only want to update the list of available tags if
           // - We haven't set any tags yet
           // - We've received the "refreshTags" flag which will force a refresh of the tags list when an agent is unenrolled

x-pack/platform/plugins/shared/fleet/public/applications/fleet/sections/agents/agent_list_page/utils/get_kuery.test.ts

@@ -10,6 +10,7 @@ import { getKuery } from './get_kuery';
 describe('getKuery', () => {
   const search = 'base search';
   const selectedTags = ['tag_1', 'tag_2', 'tag_3'];
+  const noTags = ['No Tags'];
   const selectedAgentIds = ['agent_id1', 'agent_id2'];
   const selectedAgentPolicies = ['policy1', 'policy2', 'policy3'];
   const selectedStatus = ['healthy', 'unhealthy'];
@@ -25,6 +26,14 @@ describe('getKuery', () => {
       'fleet-agents.tags : ("tag_1" or "tag_2" or "tag_3")'
     );
   });
+  it('should return a kuery for no tags if selected', () => {
+    expect(getKuery({ selectedTags: noTags })).toEqual('((NOT fleet-agents.tags : (*)))');
+  });
+  it('should return a kuery for no tags and other tags when multiple are selected', () => {
+    expect(getKuery({ selectedTags: [...noTags, ...selectedTags] })).toEqual(
+      '((NOT fleet-agents.tags : (*)) or fleet-agents.tags : ("tag_1" or "tag_2" or "tag_3"))'
+    );
+  });
 
   it('should return a kuery with selected agent policies', () => {
     expect(getKuery({ selectedAgentPolicies })).toEqual(

x-pack/platform/plugins/shared/fleet/public/applications/fleet/sections/agents/agent_list_page/utils/get_kuery.ts

@@ -4,10 +4,14 @@
  * 2.0; you may not use this file except in compliance with the Elastic License
  * 2.0.
  */
+import { i18n } from '@kbn/i18n';
 
 import { AgentStatusKueryHelper } from '../../../../services';
 import { AGENTS_PREFIX } from '../../../../constants';
 
+const NO_TAGS_VALUE = i18n.translate('xpack.fleet.noTagsValue', {
+  defaultMessage: 'No Tags',
+});
 export const getKuery = ({
   search,
   selectedAgentPolicies,
@@ -39,9 +43,20 @@ export const getKuery = ({
     if (kueryBuilder) {
       kueryBuilder = `(${kueryBuilder}) and`;
     }
-    kueryBuilder = `${kueryBuilder} ${AGENTS_PREFIX}.tags : (${selectedTags
-      .map((tag) => `"${tag}"`)
-      .join(' or ')})`;
+    //  if the user selects no tags as one of the items, we should remove it from the initial array and have its own condition
+    if (selectedTags.includes(NO_TAGS_VALUE)) {
+      const filteredTags = selectedTags.filter((tag) => tag !== NO_TAGS_VALUE);
+      // add the no tags condition, and if there are remaining tags, also add them, otherwise add nothing else but the closing parentheses
+      kueryBuilder = `${kueryBuilder} ((NOT ${AGENTS_PREFIX}.tags : (*))${
+        filteredTags.length > 0
+          ? ` or ${AGENTS_PREFIX}.tags : (${filteredTags.map((tag) => `"${tag}"`).join(' or ')}))`
+          : ')'
+      }`;
+    } else {
+      kueryBuilder = `${kueryBuilder} ${AGENTS_PREFIX}.tags : (${selectedTags
+        .map((tag) => `"${tag}"`)
+        .join(' or ')})`;
+    }
   }
 
   if (selectedAgentIds?.length) {