[Privacy] Compare app signing certificates before restoring
backed up permissions to apps

Resubmitting with fix, see http://b/247728455#comment4 for details on
the fix and http://b/184847040#comment54 for testing rationale.

Earlier Reverted Changes:
If6f0df898:[automerge] Revert "[Privacy] Compare app signing ...
I9fe0701c1:Revert "[Privacy] Compare app signing certificates...
I4f031a63c:Revert "[Privacy] Compare app signing certificates...
Iec42d2fbb:[automerge] Revert "[Privacy] Compare app signing ...

Bug: 184847040
Test: atest CtsSecurityTestCases:PermissionBackupCertificateCheckTest
Merged-In: I9c2c261a5b766759200be0e26d6cdaafc4ce846a
Change-Id: I9c2c261a5b766759200be0e26d6cdaafc4ce846a