Add a `restore` command

[kytrinyx]

This would hit the restore endpoint in the API (not yet written - see exercism/exercism#1023) and write the files to the relevant directories.

[kytrinyx]

The API back-end for this has been implemented. See exercism/exercism#1023

[ebautistabar]

I could take care of this if you want. I don't know go, but from what I'm seeing it'd be pretty straightforward.

[kytrinyx]

It should be. I'm a bit swamped at the moment, so if you have time, that would be wonderful. If not, I expect to have time soon to get to it.

[ebautistabar]

Ok, I'll see if I can do it tomorrow.

[ebautistabar]

They are really the same commit. Please ignore fa45914. I just renamed it so this would automagically close, but apparently it still appears because of the reference number 😅