Add multilingual support for exercise descriptions

[MrSerth]

This change is inspired by the respective changes in CodeOcean.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.85%. Comparing base (5dc4094) to head (467c36d).
Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2060   +/-   ##
=======================================
  Coverage   94.85%   94.85%           
=======================================
  Files         133      133           
  Lines        3385     3385           
=======================================
  Hits         3211     3211           
  Misses        174      174           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.