fix(NcRichText): modify MENTION_START regex to work on older MobileSafari versions

[arthurlockman]

Fixes RichText causes errors on WebKit | Invalid regex #5589

This regex performs the same function as the one used before, but does not make use of negative lookbehinds and therefore should work on older MobileSafari versions.

To test, I looked first at the original mentioned regex from nextcloud server to get an idea of what the intended valid and invalid captures were. I tested both the original and modified regexes for both the server one and the one used in this component to verify that the matching groups were the same. The overall match 1 (blue highlight) is slightly different however the capture group 1 (green highlight) has the same content across both so this should be compatible.

☑️ Resolves

• Fix RichText causes errors on WebKit | Invalid regex #5589
• Fix Form isn't shown on iOS <= 16.2 nextcloud/forms#2163

🖼️ Screenshots

🏚️ Before	🏡 After

🏁 Checklist

• ⛑️ Tests are included or are not applicable
• 📘 Component documentation has been extended, updated or is not applicable
• 3️⃣ Backport to next requested with a Vue 3 upgrade

[arthurlockman]

To add: I manually edited the minified JS on one of the instances I administer to the new regex pattern and the forms issue I linked is resolved!

[Antreesy]

Failed tests show that a whitespace (which is now a part of matching group) is trimmed

[arthurlockman]

Roger roger, will fix.

[arthurlockman]

Tests now pass with this new iteration. It's using positive lookaheads which have been supported in MobileSafari since the beginning. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Regular_expressions/Lookahead_assertion

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 37.86%. Comparing base (957f0ac) to head (38d3afe).
Report is 785 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5976      +/-   ##
==========================================
- Coverage   38.62%   37.86%   -0.77%     
==========================================
  Files         142      148       +6     
  Lines        4958     5261     +303     
  Branches     1497     1577      +80     
==========================================
+ Hits         1915     1992      +77     
- Misses       2954     3185     +231     
+ Partials       89       84       -5     

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[Antreesy]

Checked test examples with both regex rules, seems to return the same matching groups now. Thanks for the contribution!

Could you try to pull the latest master and rebase your PR on it? Codecov shouldn't be triggered here

[susnux]

/backport to next

[arthurlockman]

Thanks for rebasing! Glad I could help sort this out. It was affecting forms users on one of the instances I manage.

[Iwios]

Hello can I manually modify files?
It's really blocking

[susnux]

It is already fixed since a couple of versions, where do you experience this issue?