feat: rewrite pixi-build-ros in Rust

[Hofer-Julian]

Description

We expect the following benefits:

• faster build env setup for the user
• lower maintenance burden

How Has This Been Tested?

I adapted and ran the tests.

I also ran pixi install --all on the following repos with the overridden backend and made sure the metadata calls are equivalent:

• https://github.com/ros-wg-delib/rl_deliberation
• https://github.com/2lian/Motion-Stack
• https://github.com/YubanMV/aic_ASG
• https://github.com/rewire-run/rewire-custom-mappings-example
• https://github.com/ruben-arts/ros_workspace (with this one I also executed it locally)

AI Disclosure

• This PR contains AI-generated content.
  • I have tested any AI-generated content in my PR.
  • I take responsibility for any AI-generated content in my PR.

Tools: {e.g., Claude, Codex, GitHub Copilot, ChatGPT, etc.}

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added sufficient tests to cover my changes.