Changes to @hydra.main() and hydra.initialize()

Prior to Hydra 1.2, @hydra.main() and hydra.initialize() default config path was the directory containing the Python app (calling @hydra.main() or hydra.initialize()). Starting with Hydra 1.1 we give control over the default config path, and starting with Hydra 1.2, with version_base >= "1.2", we choose a default config_path=None, indicating that no directory should be added to the config search path.