Rollup merge of #122801 - celinval:smir-pretty, r=compiler-errors

Fix misc printing issues in emit=stable_mir

Trying to continue the work that ````@ouz-a```` started here: rust-lang/rust#118364

Few modifications beyond fixes:
1. I made the `pretty_*` functions private.
2. I added a function to print the instance body
3. Changed a bunch of signatures to write to the writer directly.
4. Added a function to translate the place to its internal representation, so we could use the internal debug implementation.
5. Also removed `pretty_ty`, replaced by Display implementation of Ty which uses the internal display.

Author: matthiaskrgr