Merge #8162

8162: Compute more mathematically well-rounded notion of transitive deps r=Veykril a=matklad

By including the crate itself, we make the resulting set closed with
respect to `transitve_reveres_dependencies` operation, as it becomes a
proper transitive closure. This just feels more proper and mathy.

And, indeed, this actually allows us to simplify call sites somewhat.

Co-authored-by: Aleksey Kladov <aleksey.kladov@gmail.com>