Feat/add deletion_protection to keycloak realm

[tuankiettruong]

Added deletion_protection to prevent keycloak_realm resource from being deleted, even by removing resource from, which Terraform's life_cycle.prevent_destroy does not support

[sschu]

@tuankiettruong Can you elaborate why you think this is necessary? Terraform will tell you if your plan destroys a realm so you can react accordingly.

[tuankiettruong]

If the plan output contains a lot of resources, it could be overlooked, and people still can delete it by mistake. Since a realm contains other resources like users, groups, events, so I think it would be good to be extra careful here.