The code interacting with the test runners now resides in closer
proximity to the code it is invoking. We also purge testing
functionality from mozbuild, which is where it never really belonged.
--HG--
rename : python/mozbuild/mozbuild/testing/reftest.py => layout/tools/reftest/mach_commands.py
rename : python/mozbuild/mozbuild/testing/mochitest.py => testing/mochitest/mach_commands.py
rename : python/mozbuild/mozbuild/testing/xpcshell.py => testing/xpcshell/mach_commands.py
