add a bean-discovery-mode 'scoped'

This is for some future CDI release.

We currently only have 3 bean-discovery-modes

• none
• all
• annotated

The spec also currently says that ProcessAnnotatedType will only get fired (12.4) for
• each Java class, interface or enum deployed in an explicit bean archive, and
• each Java class with a bean defining annotation in an implicit bean archive.
• each session bean

Which means that we do not get the ProcessAnnotatedType (PAT) event for any class in an 'annotated' or 'implicit' BDA which does not have a bean defining annotation.

It might be useful to fire the ProcessAnnotatedType for all classes, but do not pick them up as Beans if they (after PAT) do not have a valid scope. Effectively doing the processing but not make them @Dependent automatically if there is no scope annotation at the end of the PAT processing.

I'm not yet 100% sure how important this distinction is in practice. Just writing this up to not forget about the idea...