Include last focused id to each Event in FillEventHistory.

When the flag is enabled, we include the last focused id into useful events like selection, shown, etc as part of FillEventHistory.

Flag: android.service.autofill.add_last_focused_id_to_fill_event_history
Test: atest CtsAutoFillServiceTestCases
Bug: 334141398
Change-Id: Ie1c217248f7b0b7787ea2a04880d4edc40c5d32e