Auto merge of #134625 - compiler-errors:unsafe-binders-ty, r=oli-obk

Begin to implement type system layer of unsafe binders

Mostly TODOs, but there's a lot of match arms that are basically just noops so I wanted to split these out before I put up the MIR lowering/projection part of this logic.

r? oli-obk

Tracking:

- https://github.com/rust-lang/rust/issues/130516

compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs

@@ -432,6 +432,7 @@ fn push_debuginfo_type_name<'tcx>(
                 push_closure_or_coroutine_name(tcx, def_id, args, qualified, output, visited);
             }
         }
+        ty::UnsafeBinder(_) => todo!("FIXME(unsafe_binders)"),
         ty::Param(_)
         | ty::Error(_)
         | ty::Infer(_)