As we are rolling out the user profile feature, we'd like to expand the [Usage API](https://www.elastic.co/guide/en/elasticsearch/reference/current/usage-api.html) to report usage stats of user profiles such as (1) number of enabled user profiles and (2) number of user profiles that are [activated](https://www.elastic.co/guide/en/elasticsearch/reference/current/security-api-activate-user-profile.html) over the past X days. 

Response of the Usage API already contains a `security` field that groups relevant stats from security related features. We expect the new stats for user profiles should be added under it as well, for example:
```
{
  "security: {
    "user_profile": {
      "activated": 78,
      "recently_activated": 42  <1>
    }
  }
}
```
<1> The use of `recently_` is chosen to avoid the field to be tied to a specific time period so it is easier to evolve the definition in future.

x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/Security.java
components.add(indexServiceAccountTokenStore);
        final FileServiceAccountTokenStore fileServiceAccountTokenStore = new FileServiceAccountTokenStore(
            environment,
            resourceWatcherService,
            threadPool,
            clusterService,
            cacheInvalidatorRegistry
        );
        components.add(fileServiceAccountTokenStore);
        final ServiceAccountService serviceAccountService = new ServiceAccountService(
            client,
            fileServiceAccountTokenStore,
            indexServiceAccountTokenStore
        );
        components.add(serviceAccountService);
        final RoleProviders roleProviders = new RoleProviders(
            reservedRolesStore,
            fileRolesStore,
            nativeRolesStore,
            customRoleProviders,
            getLicenseState()
        );
        final CompositeRolesStore allRolesStore = new CompositeRolesStore(
            settings,
            roleProviders,
            privilegeStore,
            threadPool.getThreadContext(),
            getLicenseState(),
            fieldPermissionsCache,
            apiKeyService,