Rollup merge of rust-lang#93006 - michaelwoerister:fix-unsized-ptr-debuginfo, r=davidtwco,oli-obk

Fix debuginfo for pointers/references to unsized types

This PR makes the compiler emit fat pointer debuginfo in all cases. Before, we sometimes got thin-pointer debuginfo, making it impossible to fully interpret the pointed to memory in debuggers. The code is actually cleaner now, especially around generation of trait object pointer debuginfo.

Fixes rust-lang#92718

~~Blocked on rust-lang#92729

Author: matthiaskrgr