Auto merge of #6105 - bugadani:sus-char, r=ebroto

Auto merge of #6105 - bugadani:sus-char, r=ebroto

Lint for invisible Unicode characters other than ZWSP

This PR extends the existing `zero_width_space` lint to look for other invisible characters as well (in this case, `\\u{ad}` soft hyphen.

I feel like this lint is the logical place to add the check, but I also realize the lint name is not particularly flexible, but I also understand that it shouldn't be renamed for compatibility reasons.

Open questions:
 - What other characters should trigger the lint?
 - What should be done with the lint name?
 - How to indicate the change in functionality?

Motivation behind this PR: https://github.com/rust-lang/rust/issues/77417 - I managed to shoot myself in the foot by an invisible character pasted into my test case.

changelog: rename [`zero_width_space`] to [`invisible_characters`] and add SHY and WJ to the list.