Protect and prevent app's activity token

Protect and prevent app's activity token passed to an untrusted app
process. And refine the starting PendingIntent flow in the SaveUi.

Fixes: 138430575
Fixes: 138431151
Test: atest CtsAutoFillServiceTestCases
Change-Id: I809ab30417959591b396dce90605f051d35611c1
3 files changed