feat: Add required_actions attribute to keycloak_user

[scheying]

Add an option to set Required Actions on a per-user basis, like this:

resource "keycloak_user" "this" {
  username = "my-user"

  required_actions = ["CONFIGURE_TOTP"]
}

[scheying]

...finally ✅ 😃

[oliverbaehler]

@mrparkers Can this be merged? Also looking for that feature :)