Adding CLI and Plugin system

[wunder957]

Description

Resolves #43

Motivation and Context

How has this been tested?

Types of changes

• Maintenance (no change in code, maintain the project's CI, docs, etc.)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[sweep-ai]

Apply Sweep Rules to your PR?

• Apply: All new business logic should have corresponding unit tests.
• Apply: Refactor large functions to be more modular.
• Apply: Add docstrings to all functions and file headers.

[wunder957]

@MooooCat @Guo-Yunzhe Ping

As the development is not yet complete, the CLI only implements some of the features

The plugin system works fine, in the example/extension folder I have provided a minimal plugin project