optimum-cli print the help of subcommands

[michaelbenayoun]

What does this PR do?

The Optimum CLI was not printing the proper help message for subcommands.

Example command:

optimum-cli export

Before #928

Before adding the register mechanism to the CLI, the above command would give:

usage: optimum-cli <command> [<args>]

positional arguments:
  {export,env,onnxruntime}
                        optimum-cli command helpers
    export              Export PyTorch and TensorFlow models to several format (currently supported: onnx).
    env                 Get information about the environment used.
    onnxruntime         ONNX Runtime optimize and quantize utilities.

options:
  -h, --help            show this help message and exit

After #928

Now, after adding the register mechanism, it gives:

Traceback (most recent call last):
  File "/home/michael/micromamba/envs/optimum/bin/optimum-cli", line 8, in <module>
    sys.exit(main())
  File "/home/michael/projects/optimum/optimum/commands/optimum_cli.py", line 167, in main
    service.run()
  File "/home/michael/projects/optimum/optimum/commands/base.py", line 131, in run
    raise NotImplementedError()
NotImplementedError

With this PR

With this PR, it gives:

usage: optimum-cli export [-h] {onnx,tflite} ...

positional arguments:
  {onnx,tflite}
    onnx         Export PyTorch and TensorFlow to ONNX.
    tflite       Export TensorFlow to TensorFlow Lite.

options:
  -h, --help     show this help message and exit

[HuggingFaceDocBuilderDev]

The documentation is not available anymore as the PR was closed or merged.

[fxmarty]

Awesome!