get: support git remotes

[dberenbaum]

It would be nice to support dvc get origin models/model.h5. It seems unnecessary to have to type out the full URL for a known Git remote.

Edit: The context for this request is in treeverse/dvc.org#3593.

[daavoo]

How would you differentiate the git remote name from a local path?

From https://dvc.org/doc/command-reference/get#description:

url can also be a local file system path (including the current project e.g. .).

[dberenbaum]

Hm, good point. A couple possible options:

• Use -g option and make URL optional in that case.
• Introduce some new syntax like git:origin.

[karajan1001]

-g/--git-remote <git_remote> to keep consistent with other commands (dvc exp remove) .