Block deletion of permissions and roles if they are granted?

[christophermaier]

The operable:role chat command prevents deletion of the role if it is granted to any users or groups. This functionality exists only in the chat command, and not in the API.

If this kind of functionality is desirable, we should build it into the API (probably with the option to force a deletion) and expose this for every way we provide to interact with the system.

If we decide to go that route, we should (for consistency's sake) extend this to permissions, and possibly to groups (don't delete if there are members).