business rule : add criterion "requester in group"

Currently, in business rules, you can check if a requester is (or not), contains (or not), begins/ends with, matches (or not) $something, or if it exists (or not).

It would be great to be able to check if the requester is a member of a specified group.

It could possibly also be useful to be able to check it for "assigned to" or "observers", I assume this wouldn't cost mush more, although I have no usecase in mind for this.