CA-203169: Add 'pv_drivers_detected' field to Vm.t
CA-203169: Add 'pv_drivers_detected' field to Vm.t

Determining whether the PV drivers are detected in xenopsd is more lightweight
than exporting the guest's entire 'devices' xenstore subtree and xapi deducing
it.

Signed-off-by: Jonathan Davies <d3af50858a27f644d377a39d1fbd399608163688@citrix.com>

johnelse/xcp-idl,euanh/xcp-idl,xapi-project/message-switch,xapi-project/message-switch,xapi-project/message-switch