Fix fast up-to-date-check

[gitfool]

Fixes #322.

I looked into fast up-to-date-check and I think the ideal is to track the same inputs and outputs used for incremental builds, so I refactored the git info targets to use the utdc design-time targets to dynamically add the git inputs marked with utdc metadata. Furthermore, I put them in to their own utdc group to correlate the git info specific inputs and outputs.

I removed the git head cache since during my debugging I saw warnings like InputModifiedSinceLastSuccessfulBuildStart which indicated it was a bad idea. Besides, the utdc cache is only updated during design-time builds, which I could only trigger by editing the project file itself. This is also why I didn't include inputs from refs/heads/** or refs/tags/** since adding or deleting branches or tags wouldn't be picked up until the next design-time build, which can be annoying/confusing. I think it would be good to merge the git dirty cache into the git info cache for the same reasons but I left that for now, although I did add that file to the utdc inputs anyway.

[kzu]

Very nice improvement! Thanks a lot for your contribution(s!) 💪