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
return MapperPlugin.NOOP_FIELD_PREDICATE;
                }
                IndicesAccessControl.IndexAccessControl indexPermissions = indicesAccessControl.getIndexPermissions(index);
                if (indexPermissions == null) {
                    return MapperPlugin.NOOP_FIELD_PREDICATE;
                }
                if (indexPermissions.isGranted() == false) {
                    throw new IllegalStateException("unexpected call to getFieldFilter for index [" + index + "] which is not granted");
                }
                FieldPermissions fieldPermissions = indexPermissions.getFieldPermissions();
                if (fieldPermissions.hasFieldLevelSecurity() == false) {
                    return MapperPlugin.NOOP_FIELD_PREDICATE;
                }
                if (FIELD_LEVEL_SECURITY_FEATURE.checkWithoutTracking(licenseState) == false) {
                    
                    return MapperPlugin.NOOP_FIELD_PREDICATE;
                }
                return fieldPermissions::grantsAccessTo;
            };
        }
        return MapperPlugin.super.getFieldFilter();
    }
    @Override
    public BiConsumer<DiscoveryNode, ClusterState> getJoinValidator() {
        if (enabled) {
            return new ValidateLicenseForFIPS(XPackSettings.FIPS_MODE_ENABLED.get(settings));
        }
        return null;
    }
    static final class ValidateLicenseForFIPS implements BiConsumer<DiscoveryNode, ClusterState> {