Add Pause/Resume functions for VM trait. For KVM it
will be empty implementations. For MSHV it needs to freeze
and unfreeze the partition.

Signed-off-by: Muminul Islam <muislam@microsoft.com>

Implementing pause/Resume API for MSHV.
Here we set/reset the partition property(TIME_FREEZE)

Signed-off-by: Muminul Islam <muislam@microsoft.com>

Create a partition frozen always, then unfreeze the partition
during boot phase or resume phase. We also freeze the
partition during pause event. Time is freeze during the
time between freeze and unfreeze.

Signed-off-by: Muminul Islam <muislam@microsoft.com>

For MSHV we always create frozen partition, so we
resume the VM during boot. Also during pause and resume
VM events we call hypervisor specific API.

Signed-off-by: Muminul Islam <muislam@microsoft.com>