Add @EnforcePermission linter

This linter ensures that any class (or method) that extends (or
overrides) another one annotated with @EnforcePermission, is also
annotated with the exact same annotation. The intent is to surface the
permissions verified at lower-level to the service implementation.

Test: atest --host com.google.android.lint.EnforcePermissionDetectorTest
Bug: 197828948
Change-Id: I042b7e5d99bae05681869f13702d1c169b8bdb05