Restore support for PSR-0-style test-classes (#5020)

[totten]

As per #5020, this PR fixes loading of test-classes which have underscore-based namespacing (e.g. loading CRM_Utils_StringTest in file tests/phpunit/CRM/Utils/StringTest.php from example repo https://github.com/totten/phpunit-underscore-namespace). The PR also adds an end-to-end regression test.

Note: The patch for main is very slightly different (and slightly shorter). I've only opened the PR for 9.x (since that's the older version with the bug), but you can see main patches at https://github.com/totten/phpunit/commits/main-psr0

[codecov]

Codecov Report

Merging #5021 (7b49c19) into 9.5 (542bc07) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##                9.5    #5021   +/-   ##
=========================================
  Coverage     83.96%   83.97%           
- Complexity     4611     4614    +3     
=========================================
  Files           272      272           
  Lines         11464    11468    +4     
=========================================
+ Hits           9626     9630    +4     
  Misses         1838     1838           

Impacted Files	Coverage Δ
src/Framework/TestSuite.php	82.99% <100.00%> (+0.05%)	⬆️
src/Runner/StandardTestSuiteLoader.php	87.87% <100.00%> (+1.21%)	⬆️

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[sebastianbergmann]

@realFlowControl Do you have feedback on this? Thanks!

[realFlowControl]

Looks good to me.

I don't know if we actually need my suggested comment, but I would at least help the future @realFlowControl 😉

[totten]

@sebastianbergmann - Comments were updated following @realFlowControl's suggestion. (If it helps, I also added comments on the main-psr0 variant of this branch.)

It should be OK to re-run the test?

[sebastianbergmann]

Thank you! I have merged this into the 9.5 branch.

However, the patch cannot simply be merged into main for PHPUnit 10. I will accept a pull request for main that restores support for PEAR-style test-classes, but I will not work on this myself.

[totten]

Thank you @sebastianbergmann! I've submitted the port as #5030.