Support starting a workspace from a Git URL

[csweichel]

Is your feature request related to a problem? Please describe.
run-gp requires a local working copy to be present before it can work. Instead, users could provide a Git URL which we'd clone.

In effect this feature could be built out akin to Gitpod's context parser functionality.
If we were to build this, we could feed that context parser back to Gitpod.

Info
Not supporting Git context URLs was a conscious decision to keep things simple. We'd have to tread a fine line to not end up replicating Gitpod's functionality.