Allow virsh commands from the VirtualPowerDriver

The baremetal VirtualPowerDriver runs more commands then we had
previously allowed. It also runs shell pipelines which we had not
supported.

To support this we add an RE_COMMANDS dict which takes the original
command (and thus can in principle do custom translations).

Change-Id: I6bb3a46d9a04132dce819c94f9fd280919e9b7f0
Co-Authored-By: Robert Collins <rbtcollins@hp.com>
Merge "Allow virsh commands from the VirtualPowerDriver"