Deletion of all objects when realm is being removed

[vramik]

Currently when realm is deleted in MapRealmProvider.removeRealm there is following code:

...
session.users().preRemove(realm);
session.clients().removeClients(realm);
session.clientScopes().removeClientScopes(realm);
session.roles().removeRoles(realm);
realm.getTopLevelGroupsStream().forEach(realm::removeGroup);
...

During implementaion of jpa authz store, removal of all authz objects from particular realm would require addition of

if (Profile.isFeatureEnabled(Profile.Feature.AUTHORIZATION)) {
    session.getProvider(AuthorizationProvider.class).getStoreFactory().preRemove(realm);
}

before the code above. The reason for that is that session.clients().removeClients(realm); removes clients one by one and ClientRemovedEvent is published. Then in ClientApplicationSynchronizer.synchronize the event is handled. There all ResourceServers are beeing removed one by one by Client.

The Idea from @hmlnarik was to remove all code above from MapRealmProvider.removeRealm and replace it by publishing new RealmPreRemoveEvent.

[vramik]

Due to fact that event processing would be limited to server-level ProviderFactories, not component-level factories, we should rather utilize session.invalidate mechanism, which distributes the invalidation call to all current InvalidationHandlers.