Add support for parsing pixi manifests

[pombredanne]

pixi is a modern take on conda packaging, with a new package manager and builder. It would be great to parse the manifests and create proper packages
See also https://github.com/prefix-dev/pixi

@wolfv FYI insights and reviews will be much appreciated!

[nk20z3]

I'm working on this.

[wolfv]

Exciting! Do let us know if you need any help. py-rattler might be useful if you need proper Pixi.lock file parsing :)

[nk20z3]

Exciting! Do let us know if you need any help. py-rattler might be useful if you need proper Pixi.lock file parsing :)

Absolutely, thanks!

[nk20z3]

Just to update, unfortunately I'm unable to continue the project at this time, and hope someone else can take this up.