Introduce more user management APIs

- boolean stopUser(ComponentName admin, UserHandle userHandle)
- boolean logoutUser(ComponentName admin)
- List<UserHandle> getManageableUsers(ComponentName admin)
- Introduced Injector.binderWithCleanCallingIdentity

Bug: 67580550
Test: manually try each added API with a DPC on both primary and non-prijmray user.
Test: CTS tracked in b/67581357
Change-Id: I9789b9b29978d47bc22be6ecad6c5577e0f8eb5b