Rollup merge of #145033 - nnethercote:fix-144994, r=fmease

Reimplement `print_region` in `type_name.rs`.

Broken by rust-lang/rust#144776; this is reachable after all.

Fixes rust-lang/rust#144994.

The commit also adds a lot more cases to the `type-name-basic.rs`, because it's currently very anaemic. This includes some cases where region omission does very badly; these are marked with FIXME.

r? `@fmease`

Author: Zalathar