need to address lack of declarative tool to interact with Keycloak

This is a topic which we discussed many times in the past, but there was recently yet another occurence of this pain point: !1987 (comment 1904967636).

So I'm filing this issue to have a place to track this topic.

We can't viably keep piling up kube-job script to compensate for the lack of a declarative tool to interact with Keycloak.

We should invest time into find either a properly declarative way of updating things in Keycloak: an operator, something based on Crossplane (EDIT: @mihai.zaharia started to explore something like that in !2670 (closed) ), or a combination of Flux/Terraform-OpenTofu with an existing Terraform/OpenTofu Keycloak provider).... or find an alternative to Keycloak.

/cc @alain.thioliere @mihai.zaharia @samuelbartel