Use native PHPUnit Configuration class

[Slamdunk]

Closes #470

See #148 (comment)

[codecov]

Codecov Report

Merging #496 into master will decrease coverage by 1.77%.
The diff coverage is 94.20%.

@@             Coverage Diff              @@
##             master     #496      +/-   ##
============================================
- Coverage     92.65%   90.87%   -1.78%     
+ Complexity      676      650      -26     
============================================
  Files            34       33       -1     
  Lines          1797     1743      -54     
============================================
- Hits           1665     1584      -81     
- Misses          132      159      +27     

Impacted Files	Coverage Δ	Complexity Δ
src/Runners/PHPUnit/TestMethod.php	86.66% <ø> (ø)	8.00 <0.00> (ø)
src/Runners/PHPUnit/Worker/WrapperWorker.php	82.00% <ø> (ø)	22.00 <0.00> (ø)
src/Runners/PHPUnit/SuiteLoader.php	97.70% <92.85%> (-1.62%)	84.00 <6.00> (+11.00)	⬇️
src/Console/Testers/PHPUnit.php	97.52% <94.11%> (-0.87%)	40.00 <6.00> (ø)
src/Runners/PHPUnit/BaseRunner.php	91.52% <100.00%> (ø)	24.00 <0.00> (ø)
src/Runners/PHPUnit/ExecutableTest.php	83.33% <100.00%> (+0.40%)	40.00 <0.00> (+1.00)
src/Runners/PHPUnit/Options.php	91.40% <100.00%> (-0.07%)	44.00 <0.00> (ø)
src/Runners/PHPUnit/ResultPrinter.php	89.53% <100.00%> (ø)	61.00 <0.00> (ø)
src/Runners/PHPUnit/SuitePath.php	0.00% <0.00%> (-100.00%)	6.00% <0.00%> (ø%)
src/Runners/PHPUnit/TestFileLoader.php	71.79% <0.00%> (-28.21%)	19.00% <0.00%> (ø%)

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