Add tests for MyQuizzes (My Tests)

[jacbn]

Adds some tests for My Tests.

Note this uses the await renderTestEnvironment syntax introduced in the react-router upgrade so we don't need to rewrite these tests again later. As such, might be worth waiting until that's merged, then pointing this branch at main.

[codecov]

Codecov Report

❌ Patch coverage is 62.50000% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 43.17%. Comparing base (32598bd) to head (edd6c6d).
⚠️ Report is 24 commits behind head on main.

Files with missing lines	Patch %	Lines
src/app/components/elements/Tabs.tsx	53.84%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1902      +/-   ##
==========================================
+ Coverage   42.49%   43.17%   +0.68%     
==========================================
  Files         575      576       +1     
  Lines       24549    24581      +32     
  Branches     8090     8125      +35     
==========================================
+ Hits        10433    10614     +181     
- Misses      13450    13918     +468     
+ Partials      666       49     -617     

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