Move hibernation classes to v31 package

To prevent hibernation classes from being counted under testing coverage
for S-on-R tests, we move these classes to a v31 specific package which
will automatically be excluded.

Bug: 229664579
Test: builds, atest AppHibernationIntegrationTest, atest
PermissionControllerMockingTests

Change-Id: Ida95793174fb1b4e2ba00ceb98c4c82c6051be20