Add unit tests for data/ provider and filter classes

[WarLikeLaux]

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	❌
Fixed issues

What does this PR do?

Add and tighten tests for data/ classes: ArrayDataProvider, Sort, BaseDataProvider, DataFilter, ActiveDataFilter.

Coverage

File	Tests	Lines	MSI
ArrayDataProvider.php	6 → 7	16/17 (94%) → 17/17 (100%)	69% → 87%
Sort.php	21 → 29	88/102 (86%) → 102/102 (100%)	95% → 97%
BaseDataProvider.php	1 → 20	5/48 (10%) → 48/48 (100%)	50% → 90%
DataFilter.php	34 → 57	147/192 (77%) → 183/192 (95%)	70% → 73%
ActiveDataFilter.php	10 → 12	45/49 (92%) → 49/49 (100%)	82% → 82%

DataFilter remaining 9 uncovered lines are in filterAttributeValue() - a protected method only called by ActiveDataFilter. Covered by ActiveDataFilterTest but not visible in per-file coverage.

Changelog not required, because no source files changed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.82%. Comparing base (068c5a4) to head (af970d6).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #20784      +/-   ##
============================================
+ Coverage     78.62%   78.82%   +0.19%     
  Complexity    11566    11566              
============================================
  Files           376      376              
  Lines         30748    30748              
============================================
+ Hits          24176    24237      +61     
+ Misses         6572     6511      -61     

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

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.