Implement group by user query for keycloak

Hi,
I'm using Flowable in my Spring-Boot application with Keycloak as IDM.
Later, I discovered that the assignment of tasks to a group isn't working as expected.
Also I was wondering, why the idm app shows all groups, but each group contains all users.
After a bit of research, I found out, that the Keycloak integration is still WIP.

Here are the query filters, if anyone is wondering:

https://github.com/flowable/flowable-engine/blob/145abf504c84c7e60de0e2ae70a9a05db918857b/modules/flowable-ui/flowable-ui-idm-logic/src/main/java/org/flowable/ui/idm/service/keycloak/KeycloakGroupQueryImpl.java#L154

https://github.com/flowable/flowable-engine/blob/145abf504c84c7e60de0e2ae70a9a05db918857b/modules/flowable-ui/flowable-ui-idm-logic/src/main/java/org/flowable/ui/idm/service/keycloak/KeycloakUserQueryImpl.java#L133

Also, I'm very sorry for writing the original issue in a _demanding_ and unfriendly way. I was investigation a bug in our software and took the completeness of the feature for granted. I and the whole team want so say thank you for providing Flowable as open source.

Inizia con KeycloakGroupQueryImpl.java e KeycloakUserQueryImpl.java nelle posizioni query-filter collegate. Esamina come le query dei gruppi e degli utenti gestiscono il comportamento group-by-user richiesto. Il lavoro è completato quando i risultati dei gruppi Keycloak riflettono i loro utenti effettivi e l'assegnazione delle attività ai gruppi funziona come previsto.

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