[cli] added distributed launcher command (#791)

* [CLI] add CLI launcher

* Revert "[CLI] add CLI launcher"

This reverts commit df7e6506d4.

* [CLI]add cli launcher feature

* remove testing message used during developing

* refactor the module structure.

setup.py

@@ -213,6 +213,10 @@ setup(
     ext_modules=ext_modules,
     cmdclass={'build_ext': BuildExtension} if ext_modules else {},
     install_requires=fetch_requirements('requirements/requirements.txt'),
+    entry_points='''
+        [console_scripts]
+        colossal=colossalai.cli.cli:cli
+    ''',
     python_requires='>=3.7',
     classifiers=[
         'Programming Language :: Python :: 3',