Move /osquery/python_tests/* to /tools/tests
Move test_extensions process controls to test_base module
Use test_base.Testing to implement each module's main()
- This applies a default argparse with --build
- test_base.ARGS is the argparse-parsed namespace
- Use test_base.ARGS.build for the platform-specific dir
Move WatchdogTests to /tools/tests/test_watchdog.py