Adjust keycloak_required_action resource to not use metaparameter alias

[TuningYourCode]

This PR will adjust the keycloak_required_action resource that it no longer uses the alias metaparameter which leads to problems if you want to manage the same required action on multiple realms.

The github issue #320 shows the exact code and error. I tested serveral ways but the current version does not allow to manage the same required action on multiple realms.

Fixes #320

[TuningYourCode]

This PR might be interpreted as breaking change as it might lead to issues if somebody was setting alias to another value than provider_id. Anyway it should be a pretty rare condition as provider_id needs to be an exact value matching a keycloak required action "identifier".

Also the code example in the keycloak_required_action provider was setting alias and provider_id to the same name.

There might be two options to solve the underlying issue:

1. Use provider_id also for alias in all REST API calls (this PR)
2. Map API field alias to some resource attribut not being part of the meta parameters of puppet (also breaking change)