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
PageCacheRecycler pageCacheRecycler,
        CircuitBreakerService circuitBreakerService,
        NamedWriteableRegistry namedWriteableRegistry,
        NetworkService networkService
    ) {
        if (enabled == false) { 
            return Collections.emptyMap();
        }
        IPFilter ipFilter = this.ipFilter.get();
        return Map.of(
            
            SecurityField.NAME4,
            () -> {
                transportReference.set(
                    new SecurityNetty4ServerTransport(
                        settings,
                        Version.CURRENT,
                        threadPool,
                        networkService,
                        pageCacheRecycler,
                        namedWriteableRegistry,
                        circuitBreakerService,
                        ipFilter,
                        getSslService(),
                        getNettySharedGroupFactory(settings)
                    )
                );
                return transportReference.get();
            }
        );