Add MaskGCT model, inference, README

[HeCheng0625]

✨ Description

Add MaskGCT model, inference, checkpoints, and README

🚧 Related Issues

None

👨‍💻 Changes Proposed

• Add MaskGCT
• Add Amphion Codec

🧑‍🤝‍🧑 Who Can Review?

@RMSnow @jiaqili3 @zhizhengwu

🛠 TODO

• Add model and inference code
• Add README
• Add checkpoint
• Add Gradio Demo

✅ Checklist

• Code has been reviewed
• Code complies with the project's code standards and best practices
• Code has passed all tests
• Code does not affect the normal use of existing features
• Code has been commented properly
• Documentation has been updated (if applicable)
• Demo/checkpoint has been attached (if applicable)

[yuantuo666]

Change Chinese comments into English ones? These appear many times.

[yuantuo666]

Try this to disable file mode change detection: https://stackoverflow.com/questions/1580596/how-do-i-make-git-ignore-file-mode-chmod-changes