Make mocha-parallel-tests mocha-independent 🙀🍿👻

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Boom! Of course this is not as bad as it sounds. This issue assumes we need to start integrate closer with mocha and try to add the --parallel flag to mocha package which will execute the tests in mocha-parallel-tests. To do this we need to extract the main functionality of mocha-parallel-tests into a separate package which should accept mocha as a dependency (dependency injection), so that we don't need it in peerDependencies. mocha-parallel-tests will require this package and use it, as well as mocha.