feature: add git-lfs support for git:// context

[wwade]

Git repos using git-lfs are not currently supported. Unfortunately, because git proper doesn't know anything about git-lfs, the build succeeds, but the pointer files are left in place of actual file content, producing unusable images.

[lappazos]

is there a solution for that?

[healermagnus]

Yes, we really need this!