Keycloak admin client combined with devservices

[appiepollo14]

Description

Keycloak authorization has devservices, which will start a container running keycloak and configure the Application properties needed to connect to the instance.

The keyclient admin client extension don't behave that way. Especially combined with keycloak authorization, that's a hassle as the admin client endpoint will change everytime quarkus is restarted.

Implementation ideas

Implement the logic from the devservices for keycloak authorization in the keycloak admin client as well.

[quarkus-bot]

/cc @geoand (devservices), @pedroigor (keycloak), @sberyozkin (keycloak), @stuartwdouglas (devservices)

[sberyozkin]

@appiepollo14 I think the comment at #35390 provides a solution, I missed that comment, so I'll doc it, thanks for reminding