Prevent unintentional removal of widgets pinned by another host

appWidgetIds are only unique within the same user, which could lead to
overlaps in HSUM. This CL prevents a host from accessing widgets hosted
by an entirely different package. (A host can still access widgets
hosted by the same package but running in different user if it has
interact across users permission)

Bug: 386303131
Test: atest BackgroundActivityLaunchTest#testAppWidgetConfigNoBalBypass
Test: atest CtsAppWidgetTestCases
Flag: EXEMPT bugfix
Change-Id: I04e9a6b6b092aebae20b79eacfeb680088565e70