Overwrite AUR-repo's working directory instead of copying individual files

[PRESFIL]

Description

To fully manage the contents of the AUR repository, a rewriting approach is
needed, which affects the working folder as 1:1. Does it make any sense to use
copying files instead of overwriting the entire working folder?

Use case

The need to delete a file from the AUR repository. Now it is only possible to
overwrite the file in the repository when copying, with or without assets, but
you cannot delete file. Even if I duplicate file in the GitHub repository first,
and then delete it, will it remain in the AUR? This is very unobvious.

[KSXGitHub]

I am quite busy recently, so I am willing to accept a PR that accepts a parameter named asset_dir.

• This asset_dir should conflict with assets to avoid confusion (user is forbidden from specifying both assets and asset_dir).
• When asset_dir is specified, this tool should mirror the target repo ($target_dir/) to be like $asset_dir/:
  • In $target_dir/, files are deleted according to git ls-tree --name-only.
  • $asset_dir/.gitignore is respected when choosing which files to copy to $target_dir/.

If you have problems with the above specification, please let me know.

If you are also too busy to make a PR, then you would have to wait for quite a while.