Don't parse unviewable characters like zwsp in hashtags

[blowdart]

Describe the bug
You can use zero width joiners in hashtags, which, whilst not displayed, do separate your hashtag from a hashtag without them, causing hilarity and confusion

To Reproduce

Steps to reproduce the behaviour:

1. Go to https://zerowidthspace.me/
2. Create a hashtag like #hashtag and past in ZWSP where you like
3. Click on the hashtag in the post
4. Giggle at the search results

Expected behaviour

Non-printable characters should be stripped in hashtag parsing.

Details

Platform: Desktop, iOS
Build version: 1.70.0; Platform: web

[mary-ext]

Fixed by #3063