Add a UI for creating client credential tokens

Created an initial MR. Feedback on all parts very much welcome.

One thing of note: I had originally implemented the form as being opened in a modal, but then hit 🐛 Form validation breaks out of a dialog Active which is why I reverted that.

I guess I was on an old state of the module without 🐛 No way to limit allowed scopes for a consumer using client credentialss Active so had forgotten that scopes are required now, so adapted for that. Should be green now (but for the test failure that is also on 6.0.x)