Many of the tests use an identical disk configuration. Add a
GuestCommand::default_disks() to generate this configuration and use it
wherever possible.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This is a thin wrapper over std::process:Command which currently only
specifies the default binary but in future will handle more default
behaviour.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
