Sync to workspace command

[itowlson]

We could have a command on the OPA Policies folder node to 'Sync to Workspace' - this would re-upload all policies that had changed in the local workspace, and delete all policies that no longer existed in the local workspace. Probably exclude policies that weren't deployed using the extension.

One worry here would be if someone inadvertently synced while in the wrong workspace. We could mitigate this by annotating the policies with the source workspace name (and prompt if it didn't match), or always prompt for confirmation displaying a list what was going to change so the user could see if it was out of whack with expectations.