feat(package): implement vcs status cache

[weihanglo]

What does this PR try to resolve?

Implement a VCS status cache for cargo package.

It may not be worthy for the majority. Single file git status is generally fast.
Also, it might only benefit whoever does cargo package for the entire workspace in one cargo invocation, such as cargo package --workspace or using -Zpackage-workspace.

On some slow file systems or lower-end machines,
skipping file system access might be helpful.

However, slow file system access usually happens on Window.
And we'll only have large amount of git status when
#14981 merges and the repo contains lots of symlinks.
Given symlink handling story is crazy in real world Windows

How should we test and review this PR?

I didn't really benchmark it.
If any reviewer doesn't think it is worth the complexity,
feel free to close hits.

Additional information

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[epage]

So this only really helps us with source files outside of the package root? Is this going to buy us enough gains to be worth the performance hit?

[weihanglo]

So this only really helps us with source files outside of the package root? Is this going to buy us enough gains to be worth the performance hit?

Yes. This is kind of another speculation. It only helps in that situation and when having lots of workspace members sharing the same set of files-outside-package-root.

I lean toward closing this and then revive #14962, once #14981 has merged. The workspace inheritance issue won't be harder to fix with or without #14962

[rustbot]

☔ The latest upstream changes (possibly d85d761) made this pull request unmergeable. Please resolve the merge conflicts.

[weihanglo]

Close as it is just a speculation. Could revisit when needed. At this moment for performance I favor something like #14997