Add test for activity start with fade-in animation

Autofill should do a pre-fill request even if an activity start with
fade-in animation. That will cause the views of the activity layid out
but is invisible to the user. And then as the animation progresses, the
view becomes visible to the user.

Bug: 234429643
Test: atest android.autofillservice.cts.dialog.FadeInActivityTest
Change-Id: I8174bc1df9197d06b8f9f650d0858a4d0afcb2dc
4 files changed