Ports encryption/storage from gmscore to AOSP.

A few additional changes (apart from style and usual dependencies) were needed:
- BackupEncryptionDbHelper now extends SQLiteOpenHelper directly,
implementing relevant methods.
- Dependencies on Guava are replaced by their Java equivalents.

Bug: 111386661
Test: atest RunFrameworksServicesRoboTests
Change-Id: I4566980fc81d6cff5e7012184502e028980512ae