feat: implement doctrine-based fulltext search

[benjaminfrueh]

📝 Summary

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

Resolves #2050

🏁 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

[juliusknorr]

We use this one in a few other apps: https://github.com/search?q=org%3Anextcloud+wamania%2Fphp-stemmer&type=code

Maybe worth to consider scoping the dependency to avoid conflicts with different versions between apps. https://arthur-schiwon.de/isolating-nextcloud-app-dependencies-php-scoper

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