Update rust config to add wgs/projects

[jackh726]

I often see people do r? rust-lang/wg-traits or r? rust-lang/wg-incr-comp instead of traits or incremental. I just copied these groups from the expert map, but I think we should have at least aliases for some working groups or projects (by just making a new group with a singular member - a different group), or adding additional groups as necessary.