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
operatorPrivilegesService,
            restrictedIndices
        );
        components.add(nativeRolesStore); 
        components.add(reservedRolesStore); 
        components.add(allRolesStore); 
        components.add(authzService);
        final SecondaryAuthenticator secondaryAuthenticator = new SecondaryAuthenticator(securityContext.get(), authcService.get());
        this.secondayAuthc.set(secondaryAuthenticator);
        components.add(secondaryAuthenticator);
        ipFilter.set(new IPFilter(settings, auditTrailService, clusterService.getClusterSettings(), getLicenseState()));
        components.add(ipFilter.get());
        DestructiveOperations destructiveOperations = new DestructiveOperations(settings, clusterService.getClusterSettings());
        securityInterceptor.set(
            new SecurityServerTransportInterceptor(
                settings,
                threadPool,
                authcService.get(),
                authzService,
                getSslService(),
                securityContext.get(),
                destructiveOperations
            )
        );
        securityActionFilter.set(
            new SecurityActionFilter(
                authcService.get(),
                authzService,
                auditTrailService,
                getLicenseState(),