Add comment action to update git source track

[TheTripleV]

A new github action on comment should be added that auto commits on top to keep up with git tracking.

Example Usage:
/git-source-track wpilibsuite/allwpilib#6324
/git-source-track wpilibsuite/allwpilib#6324
/git-source-track https://github.com/wpilibsuite/allwpilib/pull/6324
/git-source-track 1e4a647918cfed98ab25de08dae83ff002f6de2d