feat: do not re-install if source does not change

[tdejager]

This should ensure that a build/rebuild is only triggered when the source is changed.

The final todo, I would say is to move the merge the reinstall_globs.rs file and the new struct that have been created in environment.rs.

[baszalmstra]

Soooo I have refactored almost everything. I had a long discussion with @wolfv today and we decided that instead of storing the caching information in the prefix itself we would store it in a cache together with the built artifact. This is then very similar to what we do with the metadata basically.

[tdejager]

Could you elaborate why :)?

[wolfv]

In my opinion the cache information doesn't really belong in the prefix information. My understanding is that we now have a two layered cache:

pixi.toml -> metadata cache -> artifact cache -> prefix

It's one more "cache" but we would have needed that cache anyways and now it can be shared across multiple projects. The cache should know when it needs to generate a new artifact based on mtime, etc, and then return a new hash that should be used as part of the package build string to be installed in the prefix.

[tdejager]

Yes that makes sense! Thanks for explaining!

[tdejager]

Nice, missing some docs mainly.