Add bitwise Int compiletime operations

[bishabosha]

No description provided.

[bishabosha]

not really sure why tests/pos/singleton-ops-test-issue-8280.scala broke

[panacekcz]

(Hope you don't mind me chiming in, I clicked the pr wondering about this.)
It fails because the type scala.compiletime.ops.int.& shadows the intersection type scala.& in Int & Singleton.
Actually, the Syntax section at http://dotty.epfl.ch/docs/reference/new-types/intersection-types-spec.html should be updated, & seems to be just a normal identifier, not a soft keyword.

[bishabosha]

& seems to be just a normal identifier, not a soft keyword.

Ah yeah, that makes total sense

[bishabosha]

what would be a more appropriate name for the int.& operation?

[OlivierBlanvillain]

BitwiseAnd and BitwiseOr?

I would also be ok with the lazy solution which would be to just require people to always write int.& and int.|.