Rollup merge of #145065 - petrochenkov:riblock, r=davidtwco

resolve: Introduce `RibKind::Block`

to avoid confusing module items, blocks with items, and blocks without items.

Addresses rust-lang/rust#143141 (comment) and rust-lang/rust#143141 (comment).

A couple of related cleanups are also added on top.

Author: Zalathar