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
}
            builder.put(SecuritySettings.addUserSettings(settings));
            return builder.build();
        } else {
            return Settings.EMPTY;
        }
    }
    @Override
    public List<Setting<?>> getSettings() {
        return getSettings(securityExtensions);
    }
    /**
     * Get the {@link Setting setting configuration} for all security components, including those defined in extensions.
     */
    public static List<Setting<?>> getSettings(List<SecurityExtension> securityExtensions) {
        List<Setting<?>> settingsList = new ArrayList<>();
        
        settingsList.add(XPackSettings.FIPS_MODE_ENABLED);
        SSLService.registerSettings(settingsList);
        
        IPFilter.addSettings(settingsList);
        
        LoggingAuditTrail.registerSettings(settingsList);
        
        AnonymousUser.addSettings(settingsList);
        settingsList.addAll(InternalRealmsSettings.getSettings());
        settingsList.addAll(JwtRealmsServiceSettings.getSettings());
        ReservedRealm.addSettings(settingsList);
        AuthenticationService.addSettings(settingsList);
        AuthorizationService.addSettings(settingsList);