[AAPM] Add help uri

This URL is used by the Advanced Protection dialog to point users to the
AAPM settings page. It is empty in the platform, and overlayed by
GoogleConfigOverlay, as the settings page is provided by GMS.

Bug: 401233918
Test atest GtsFeaturesTestCases
Flag: EXEMPT resource only

Change-Id: I3c6d24e3e9a4358ab1adb342dbee8fc56ac16794