CA-105159: Wait for ack of shutdown request for HVM guests with PV drivers

The code paths only handled fully-PV guests and HVM guests without PV drivers.
In the case of PV drivers we did not wait for the shutdown request to be
acknowledged. This did not enable early exit if the request was not
acknowledged.

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Signed-off-by: David Scott <dave.scott@eu.citrix.com>
CA-105002: Robustify against domains that are unkillable

Signed-off-by: Jon Ludlam <jonathan.ludlam@eu.citrix.com>
Signed-off-by: David Scott <dave.scott@eu.citrix.com>
CA-92550: Update xenstore permissions on /vm/<uuid> tree to reflect the new domain ID when a domain is rebooted or migrated to localhost

Signed-off-by: Euan Harris <euan.harris@citrix.com>
Signed-off-by: David Scott <dave.scott@eu.citrix.com>