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/profile/ProfileService.java
}
            }).toList(), resultsAndErrors.errors()));
        }, listener::onFailure));
    }
    
    SearchRequest buildSearchRequestForSuggest(SuggestProfilesRequest request, TaskId parentTaskId) {
        final BoolQueryBuilder query = QueryBuilders.boolQuery().filter(QueryBuilders.termQuery("user_profile.enabled", true));
        if (Strings.hasText(request.getName())) {
            query.must(
                QueryBuilders.multiMatchQuery(
                    request.getName(),
                    "user_profile.user.username",
                    "user_profile.user.username._2gram",
                    "user_profile.user.username._3gram",
                    "user_profile.user.full_name",
                    "user_profile.user.full_name._2gram",
                    "user_profile.user.full_name._3gram",
                    "user_profile.user.email"
                ).type(MultiMatchQueryBuilder.Type.BOOL_PREFIX).fuzziness(Fuzziness.AUTO)
            );
        }
        final SuggestProfilesRequest.Hint hint = request.getHint();
        if (hint != null) {
            final List<String> hintedUids = hint.getUids();
            if (hintedUids != null) {
                assert false == hintedUids.isEmpty() : "uids hint cannot be empty";
                query.should(QueryBuilders.termsQuery("user_profile.uid", hintedUids));
            }
            final Tuple<String, List<String>> label = hint.getSingleLabel();
            if (label != null) {