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
*/
    @Nullable
    private <T> T findValueFromExtensions(String valueType, Function<SecurityExtension, T> method) {
        T foundValue = null;
        String fromExtension = null;
        for (SecurityExtension extension : securityExtensions) {
            final T extensionValue = method.apply(extension);
            if (extensionValue == null) {
                continue;
            }
            if (foundValue == null) {
                foundValue = extensionValue;
                fromExtension = extension.extensionName();
            } else {
                throw new IllegalStateException(
                    "Extensions ["
                        + fromExtension
                        + "] and ["
                        + extension.extensionName()
                        + "] "
                        + " both attempted to provide a value for ["
                        + valueType
                        + "]"
                );
            }
        }
        if (foundValue == null) {
            return null;
        } else {
            logger.debug("Using [{}] [{}] from extension [{}]", valueType, foundValue, fromExtension);