refactor: use camino for paths

[ematipico]

Summary

This PR removes the use of Path and PathBuf from the majority of the code base, mostly where it counts (Workspace, CLI and LSP), and uses camino UTF-8 paths.

I did some research and other Rust-based compilers have made this choice, and the team agreed that this should be a very safe choice.

Test Plan

Existing tests should pass

[codspeed-hq]

CodSpeed Performance Report

Merging #4797 will not alter performance

_{Comparing refactor/use-camino (1f7a756) with next (93d1e23)}

Summary

✅ 97 untouched benchmarks

[ematipico]

In this PR I also changed how BiomePath is serialized and de-serialized. Before, we were forced to pass file kind and the was_written flag. This is incorrect because it's an implementation detail:

• was_written is set internally, and serializers shouldn't set it
• file_kind is set automatically when the type is created

This simplifies the APIs