Auto merge of #100064 - RalfJung:disaligned, r=petrochenkov

fix is_disaligned logic for nested packed structs

rust-lang/rust#83605 broke the `is_disaligned` logic by bailing out of the loop in `is_within_packed` early. This PR fixes that problem and adds suitable tests.

Fixes rust-lang/rust#99838

Author: bors