installd: parameterize user data snapshots with snapshot_id

- snapshot_id will be provided by RollbackManagerService and for a given
  rollback will be equal to its rollback_id.
- snapshotAppData now creates a folder to snapshot data to, in case it
  does not exist.
- removed ceDataInode from restoreAppDataSnapshot API, since it's only
  called if users phone is unlocked, meaning that CE data is available and
  doesn't require inode to be accessed.
- refactored installd_service_test to reduce test set up boilerplate.
- added a test to cover case when snapshots for different packages have
  the same snapshot_id.

Bug: 124029909
Test: installd_utils_test installd_service_test, RollbackTest
Change-Id: I4177a44a60cdfdc5429a28c613ce661b24482b8b