[ECM] Add EnhancedConfirmationManagerTest

This tests EnhancedConfirmationManager.

(NOTE: This is not a UI test, but I put it in CtsPermissionUiTestCases
for now because we have several helper methods related to installing
packages that are needed by this test. We should consider extracting
those methods into a common library later.)

Bug: 310655061
Test: atest CtsPermissionUiTestCases:android.permissionui.cts.EnhancedConfirmationManagerTest
Change-Id: I5c318f75180e5709e97bb5663d696ae656253aa8