Suggestion: Support sets of allowed and denied domains

[fabianlaule]

Hi @micedre,

thank you very much for this extension. Currently I'm facing the issue that I have to deny the registration for one domain in Keycloak. I thought that I could clone this repo and modify it for my purpose or we could extend this extension to support both variants to allow and deny specific domains.

What are your thoughts about my suggestion? If you like this suggestion I would create the PR for this feature.

Greetings
Fabian

[micedre]

This is a good idea, a PR would be more than welcome 😊