Use `pixi` to replace our bash scripts and many of the Dockerfile layers

[jleibs]

• https://github.com/rerun-io/rerun/pull/3707 seems very compelling

Pixi should be able to replace all of our current just commands while bringing the added benefit of running things in an environment with managed dependencies. For example, this gives us access to our code-gen dependencies, the arrow-cpp we need for building rerun-cpp, etc.

This lets us replace all of the commands in just with versions that handle the dep installation first. This also lets us collapse many of the layers of our Dockerfile into a single pixi install invocation.

TODO

• [x] Use pixi on CI
  • [x] C++: Reopen https://github.com/rerun-io/rerun/pull/3921
• [ ] Replace venv with pixi
• [x] #4171
• [ ] Replace scripts/requirements-dev.txt etc
• [x] #4170
• [ ] Replace our other .sh scripts, if possible (https://prefix.dev/docs/pixi/advanced/advanced_tasks)
• [ ] Publish rerun on pixi
• [ ] …

[abey79]

Vaguely relevant issue for me:

• https://github.com/prefix-dev/pixi/issues/189

[emilk]

We should probably keep our requirements.txt files, at least most of them (e.g. for examples)

[Wumpf]

the only thing we didn't do is to publish rerun on pixi itself, but otherwise we ticked all the boxes now!