git: Add ArchiveReader
Created by: ryanslade
This removes a call to gitserver.Command from outside the vcs/git package.
Part of https://github.com/sourcegraph/sourcegraph/issues/27909
Created by: ryanslade
This removes a call to gitserver.Command from outside the vcs/git package.
Part of https://github.com/sourcegraph/sourcegraph/issues/27909