Add new optional clover-html formatter.

[BlairCooper]

Fixes #1430

Add runner for PHPUnit 9
Add support for Clover HTML report.
Pass PHPUnit configuration values to filter and code coverage classes.

[codecov]

Codecov Report

Merging #1436 (4acb8a8) into master (f5ddaa1) will decrease coverage by 0.35%.
The diff coverage is 39.02%.

@@             Coverage Diff              @@
##             master    #1436      +/-   ##
============================================
- Coverage     54.20%   53.85%   -0.36%     
- Complexity     9137     9202      +65     
============================================
  Files           467      469       +2     
  Lines         22188    22337     +149     
============================================
+ Hits          12028    12030       +2     
- Misses        10160    10307     +147     

Impacted Files	Coverage Δ	Complexity Δ
...t/formatter9/CloverHtmlPHPUnitResultFormatter9.php	0.00% <0.00%> (ø)	4.00 <4.00> (?)
classes/phing/tasks/ext/phpunit/PHPUnitTask.php	34.81% <20.58%> (-3.36%)	112.00 <0.00> (+13.00)	⬇️
...ses/phing/tasks/ext/phpunit/PHPUnitTestRunner9.php	48.24% <48.24%> (ø)	53.00 <53.00> (?)
...asses/phing/tasks/ext/phpunit/FormatterElement.php	46.66% <50.00%> (+0.32%)	20.00 <0.00> (+1.00)
...ses/phing/tasks/ext/phpunit/PHPUnitTestRunner8.php	0.00% <0.00%> (-46.73%)	54.00% <0.00%> (-6.00%)

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[siad007]

Please revert the changes from the runner or do it complete - again there are missing stuff!
FYI I have fixed the coverage issue in #1437