Auto merge of #33929 - petrochenkov:pathir, r=eddyb

Auto merge of #33929 - petrochenkov:pathir, r=eddyb

Separate bindings from other patterns in HIR

Now when name resolution is done on AST, we can avoid dumping everything that looks like an identifier into `PatKind::Ident` in HIR.
`hir::PatKind::Ident` is removed, fresh bindings are now called `hir::PatKind::Binding`, everything else goes to `hir::PatKind::Path`.

I intend to do something with `PatKind::Path`/`PatKind::QPath` as well using resolution results, but it requires some audit and maybe some deeper refactoring of relevant resolution/type checking code to do it properly.
I'm submitting this part of the patch earlier to notify interested parties that I'm working on this.

cc @jseyfried
r? @eddyb