Create git-info files

[premun]

Context

As part of the tarball generation process, we are generating files that contain information about the source (for sourcelink purposes). We need to bake this step into the VMR assembly process so that these files are in place for source build to work.

Goal

For this step of the tarball generation process, we need to find a counterpart in the VMR and decide when it will happen, then implement it.