Auto merge of #127438 - compiler-errors:compute-outlives-visitor, r=lcnr

Make `push_outlives_components` into a `TypeVisitor`

This involves removing the `visited: &mut SsoHashSet<GenericArg<'tcx>>` that is being passed around the `VerifyBoundCx`. The fact that we were using it when decomposing different type tests seems sketchy, so I don't think, though it may technically result in us registering more redundant outlives components 🤷

I did end up deleting some of the comments that referred back to RFC 1214 during this refactor. I can add them back if you think they were useful.

r? lcnr

Author: bors