libsnapshot: Check if the vendor is updated from Android S for GRF

In a GRF config, if Vendor partition is updated from Android 12; post
OTA reboot, first stage init will communicate to daemon to check if the
daemon can support socket handoff. If that succeeds, then it is a signal
that the vendor has been updated from Android 12. Use a marker in
/metadata to signal that the vendor was updated. If the marker is present,
then post OTA reboot, userspace snapshot will be used.

Bug: 333854394
Test: OTA
Android U (system) + S (vendor) -> Android V (system) + V (Vendor)

Change-Id: Ie38c4379010789a84e5b44529b407f9f82135271
Signed-off-by: Akilesh Kailash <akailash@google.com>