Merge "libsnapshot_cow: Prepare device to boot from pre-created snapshots" into main am: 6b78aac2cf am: eaf919aa34 am: 87a38fab06 am: 014d68dda1 am: dc68791aeb

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2746258

Change-Id: Ifec0df916c5c670e8e23536731b7e31f2d1165f7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>