[Augmented Autofill] Add accessibility title to augmented drop down window.

Similar to how normal autofill set it in FillUi.java. After the change, the talkback would read "Window autofill option": https://screenshot.googleplex.com/ALg8LVCuH9A28HY

Change-Id: I894dfefb280879fc130f4fd404ba234303b02bca
Flag: android.service.autofill.add_accessibility_title_for_augmented_autofill_dropdown
Bug: b/375284244
Test: build && manual test (b/375284244#comment18)