Add "Role" as a way to assign reviewers access to queues

[julietshen]

Problem being solved

Adding people one-by-one to queues is very manual, takes a long time, and can lead to mistakes.

Proposed solution

To solve the immediate pain point of #383 we should allow admins/managers to use Roles as a way to assign access to queues.

This should be superseded by the addition of Groups, once that feature is scoped and defined.

Alternatives considered

Thought about building Groups as the proper solution, but we need to better define the feature first.

Anything else

No response

Screenshots

No response

Checklist

• I’ve reviewed and agree to follow the code of conduct