Add self revocation public API

Test: Manual test using a non-privileged app, atest
android.permission.cts.SelfRevokeRuntimePermissionTest

When calling the API, the permission (along with any other permissions
from the same group) for the current package is downgraded to a one-time
permission, and a one-time permission session is started.

Bug: 210387494

Change-Id: I9f061cbc8c3db720127c96200fe94a644246b6d7