Make phpunit.php less hackish, and install the listener unconditionally
* Instead of rewriting $argv, add a Command subclass called
MediaWikiPHPUnitCommand which overrides the configuration using the
stub functions in Command which were provided for that purpose.
* Revert
c804a0b5b9be8be9, which added redundant debug output to tests,
and instead install the MediaWikiPHPUnitTestListener listener
unconditionally. Deprecate and make non-functional the --debug-tests
option. If you don't want tests to produce debug output, you can
always turn the channel off.
* Because I added our listener to the listener array instead of making
it override the printer, it's no longer necessary to derive from
PHPUnit\TextUI\ResultPrinter. Instead we derive from BaseTestListener.
So we don't need to call the (empty) parent methods.
* Remove the --with-phpunitclass feature since it doesn't work with this
scheme.
* Instead of passing CLI args to MediaWikiTestCase via a public static
variable, inject it non-statically by overriding the TestRunner and
TestResult.
* Remove --file, which has been non-functional since my 2016 refactor.
Change-Id: Ibcaf9ca81c8dc63cce6dc6f6fb1fffee19f8804e