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/core/src/main/java/org/elasticsearch/xpack/core/security/SecurityFeatureSetUsage.java
if (in.getVersion().onOrAfter(Version.V_8_2_0)) {
            domainsUsage = in.readMap();
        }
    }
    public SecurityFeatureSetUsage(
        boolean enabled,
        Map<String, Object> realmsUsage,
        Map<String, Object> rolesStoreUsage,
        Map<String, Object> roleMappingStoreUsage,
        Map<String, Object> sslUsage,
        Map<String, Object> auditUsage,
        Map<String, Object> ipFilterUsage,
        Map<String, Object> anonymousUsage,
        Map<String, Object> tokenServiceUsage,
        Map<String, Object> apiKeyServiceUsage,
        Map<String, Object> fips140Usage,
        Map<String, Object> operatorPrivilegesUsage,
        Map<String, Object> domainsUsage
    ) {
        super(XPackField.SECURITY, true, enabled);
        this.realmsUsage = realmsUsage;
        this.rolesStoreUsage = rolesStoreUsage;
        this.roleMappingStoreUsage = roleMappingStoreUsage;
        this.sslUsage = sslUsage;
        this.tokenServiceUsage = tokenServiceUsage;
        this.apiKeyServiceUsage = apiKeyServiceUsage;
        this.auditUsage = auditUsage;
        this.ipFilterUsage = ipFilterUsage;
        this.anonymousUsage = anonymousUsage;
        this.fips140Usage = fips140Usage;