* keycloak: fix creating a user federation w/ idempotent id
Creating a user federation while specifying an id (that doesn't exist
yet) will fail with a 404. This commits fix this behavior.
* keycloak: fix user federation mapper duplication
This commit fixes a bug where mappers are duplicated instead of
configured when creating a user federation.
When creating a user federation, some mappers are autogenerated by
keycloak. This commit lets the keycloak_user_federation module recompute
mappers final values after the user federation is created so that the
module can try to merge them by their name.
* add missing fragment for pr #4212
