feat: implement doctrine-based fulltext search

[benjaminfrueh]

📝 Summary

Replaces TNTSearch with nextcloud database full-text search using doctrine.

Resolves #2050

Todo

• Implement language detection in stemmer
• Scope php-stemmer dependency using php-scoper
• Remove documentation about extra tntsearch dependencies
• Migrate e2e FTS tests to Playwright
• Follow-up: add Arabic stemmer

🏁 Checklist

• Code is properly formatted (npm run lint / npm run stylelint / composer run cs:check)
• Sign-off message is added to all commits
• Tests (unit, integration and/or end-to-end) passing and the changes are covered with tests
• Documentation (README or documentation) has been updated or is not required

[github-actions]

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[mejo-]

Really nice work, thanks so much @benjaminfrueh. I finally found time to go through the code changes, read up a bit on stemming, fuzzy searching, bigrams and other stuff I didn't know much about before 😆

The general approach of your implementation looks really clean and promising to me.

I have quite a few comments and questions and am curious what you think about them.

[mejo-]

Really nice work, thanks @benjaminfrueh ❤️