Reword and migrate editable errors to rich format

[ichard26]

Before:

After:

Towards #10421. ✨

[ichard26]

A general question I have is whether to let rich automatically highlight numbers, links, paths, etc. It's distracting noise for most requirements, but it could be nicer for URLs.

[pradyunsg]

A general question I have is whether to let rich automatically highlight numbers, links, paths, etc. It's distracting noise for most requirements, but it could be nicer for URLs.

For now, wrapping these in Text is reasonable -- I have a personal TODO somewhere to change the highlighter we're using in pip's rich renders to highlight specific things nicely.

[ichard26]

Actually this needs some work because (invalid) editable requirements can be created as part of userflows that don't involve installation, like pip wheel -e . (which is silly but is supported), hmm.

[ichard26]

The invalid editable error may still be confusing in the context of pip wheel, but I'm not sure how to address that without improving the error in the significantly more important case of pip install. I suppose I could tweak the error message based on what command is running, but that seems like too much engineering for an uncommon situation.

[pradyunsg]

@ichard26 Why is this PR marked as a draft?

[ichard26]

See #12811 which has the conflicts fixed + some further improvements!