Add support for webkitpy tests EWS

Add support for webkitpy tests EWS
https://bugs.webkit.org/show_bug.cgi?id=178480

Reviewed by Alexey Proskuryakov.

* Scripts/webkitpy/common/config/ews.json: Added webkitpy EWS.
* Scripts/webkitpy/common/net/generictestresults.py: Renamed from Scripts/webkitpy/common/net/bindingstestresults.py.
* Scripts/webkitpy/common/net/generictestresults_unittest.py: Renamed from Scripts/webkitpy/common/net/bindingstestresults_unittest.py.
* Scripts/webkitpy/tool/bot/patchanalysistask.py:
(PatchAnalysisTask._test_patch): Do not retry webkitpy test since they are not flaky.
* Scripts/webkitpy/tool/bot/bindingstestresultsreader.py: Updated import for BindingsTestResult.
* Scripts/webkitpy/tool/bot/retrylogic_unittest.py: Ditto.
* Scripts/webkitpy/tool/bot/webkitpytestresultsreader.py: Copied from Scripts/webkitpy/tool/bot/bindingstestresultsreader.py.
* Scripts/webkitpy/tool/commands/earlywarningsystem.py:
(AbstractEarlyWarningSystem.begin_work_queue): Added webkitpy test result reader.
* Scripts/webkitpy/tool/commands/earlywarningsystem_unittest.py: Updated unit-tests.
* Scripts/webkitpy/tool/steps/checkpatchrelevance.py: Run webkitpy EWS only for relevant changes.
* Scripts/webkitpy/tool/steps/runtests.py:
(RunTests.run): Run webkitpy tests when --group=webkitpy is passed.
(RunTests._run_webkitpy_tests): Method to invoke webkitpy tests.
* Scripts/webkitpy/tool/steps/steps_unittest.py:
(test_runtests_webkitpy): Added unit-test.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@224547 268f45cc-cd09-0410-ab3c-d52691b4dbfc