Add a condition to filter by current user role

Thanks, this is great. Definitely needs to be in for the exact use case mentioned.

A couple minor tweaks I'd request before we commit:

1. Rename the condition current_user_role.
2. Rename the class CurrentUserRole to match (along with the related comments).
3. Relabel the condition User role.
4. Let's introduce a new more general category called Current request.
5. I don't think we need the weight; I'd just remove it.

My rationale for the machine name / label mismatch is that I think "Current request" makes sense as a group (think it's better than "Global" or "Context"), and we don't need the redundant "current" in the label ... but it still makes sense to identify in the code.

My only other consideration is that since we're adding this new, we might like the opportunity to build operator selection into it. Right now the configuration element is titled Allowed roles, but we could make this two elements:

1. Matching strategy radios element with options User must have a selected role, User must have all selected roles, and User must have none of the selected roles
2. Roles checkboxes element with the various roles as options.

Addressed most of #6, but not the fancy roles operations stuff at the end. Converted to MR, hiding patches.

Implemented the separate 'Matching strategy' radios and corresponding logic changes in evaluate(). Also replaced the deprecated user_role_names() call with the recommended alternative. Light local testing is working well. Probably wants automated tests, but I don't have time for that now (about to board a flight).

Let's just shorten the keys to "any", and "all", no need for the redundant "role" in there.
We also need tests.

- Shortened the keys
- Added the missing config schema

Y'all can write tests if you need them. I'm way out of time on the project where I need this functionality, and it's working fine for me.

Cheers,
-Derek

Thanks everyone! Merged!

Automatically closed - issue fixed for 2 weeks with no activity.