Register OnOpChangedListener listener

When a user toggles permission of an unknown source to install other apps, this change is notified in the OnOpChangedListener. Register these listeners in InstallLaunch to react when user changes the install permission state.

Bug: 182205982
Test: builds successfully
Test: No CTS Tests. Flag to use new app is turned off by default

Change-Id: I20ad5123264e87b11875bfff3c2db71624cbf8a5