Add support for Cargo's new build-dir layout

[ranger-ross]

This PR adds logic to handle the new layout of Cargo's build-dir which changes the directory structure of Cargo internally.
(can be enabled with -Zbuild-dir-new-layout)

Resources

• Tracking issue Re-organize build-dir by package + hash, rather than artifact type rust-lang/cargo#15010
• Call for testing

[pacak]

Is it different from #409 ?

[pacak]

rust-lang/cargo#13672 - also related.

[ranger-ross]

Is it different from #409 ?

Yes, in #409 it added support for Cargo's build-dir.
Internally Cargo has split target into 2 directories build-dir (stabilized in Rust 1.91) and artifact-dir (still unstable)
Both of these point to target by default so user's often do not realized they are separate.

There is a separate change to restructure the file layout of build-dir to fix some long standing issues in Cargo and unblock new features. The blog post linked above has a pretty summary of the structural changes.
This PR is adding support for the new file layout (while keeping support for the old layout for backwards compatibility)

[pacak]

Seems to work. Or at least it doesn't break the existing build :)

If only cargo would pass the info about generated files - whole this guessing whack-a-mole wouldn't be necessary.

Let's merge it, I appreciate the contribution ❤️

[ranger-ross]

Thanks! And for what it's worth, your issue was called out in the known issues of the tracking issue as things we need to improve so people do not need to rely on Cargo internals.

[pacak]

0.2.57 is out.