pixi should manage its own .pixi/.gitignore

[maresb]

Problem description

Currently the user (or pixi init) must add .pixi to their .gitignore to prevent Git from tracking .pixi/. There are two issues associated with this:

1. It is a seemingly unnecessary additional installation step in light of the alternative below.
2. Whenever the user checks out a branch from before .pixi was ignored, Git will stop ignoring .pixi.

Suggested alternative:

Have pixi create a .pixi/.gitignore file to ignore all files under .pixi/. This way the .pixi/ directory becomes self-contained and unobtrusive from the Git perspective. And this makes initialization of new pixi projects simpler. (IMO you could also get by without .gitattributes so then you're down to just pixi.toml!)

Bonus: repeat with .dockerignore

[maresb]

From #questions-chat

[maresb]

Another situation where the current state of things is annoying:

I'm working on some open-source project that doesn't use pixi, so I add my own pixi.toml. Ideally I could just leave that and the rest of the pixi files untracked by Git. However, I need to modify .gitignore and be careful not to check in the changes. I rebase quite frequently, so whenever I rebase I have to stash my updated .gitignore and that causes a big mess.

[maresb]

We might not yet be able to entirely get rid of .gitignore in the project root due to .egg-info, see #1693 (comment).

[maresb]

If we get rid of .gitignore in the project root, then we will trigger pypa/hatch#304. Probably the safest approach at first is to keep both .gitignores. We could also try and add .pixi to the built-in ignores as per pypa/hatch#493.