SimpleManualPermissionEnforcementDetector: Handle simple if expressions

The previous implementation was naive and did not actually handle if
expressions.

Update the detector to look for calls to permission checks that
explicitly check against PackageManager.PERMISSION_GRANTED/DENIED and
do nothing other than throw SecurityException if the check fails.

Bug: 247537842
Test: SimpleManualPermissionEnforcementDetectorTest
Change-Id: I8cf0bd9355ee5ae91d44117a7f62a3cca0588fb9