Make sure apps cannot forge package name on AssistStructure used for Autofill.

Test: cts-tradefed run commandAndExit cts-dev -m CtsAutoFillServiceTestCases -t android.autofillservice.cts.VirtualContainerActivityTest#testAppCannotFakePackageName
Test: cts-tradefed run commandAndExit cts-dev -m CtsAutoFillServiceTestCases

Bug: 69981710

Change-Id: Id6036cddb51dd8dd0c9128b7212d573f630d693f
Merged-In: Id6036cddb51dd8dd0c9128b7212d573f630d693f