Unlinked Mentions don't handle text in blocks correctly

[WhiteNoise]

Do not show X in Unlinked mentions / Avoid backlinks detection in tags, wikilinks and md links

This is a meta-post to group together several requests about automatically excluding (not showing or remove the possibility to link) some matches in the unlinked mentions section: Matches in external markdown links [xx match xx](https://url.com) Matches in URLs http://xx.com/match/xx Matches in tags Matches within code blocks and inline code (however, now codeblocks are also used to encapsulate text not just code, like admonition. It may make sense to search in these blocks) Matches in in…