[Improve fill dialog] Get IME updates to autofill

Autofill Fill Dialog (aka Bottomsheet dialog) should show up after
IME animation finishes.  Currently, the bottomsheet may start
popping up simultaneously as the IME is animating. This change lays
the foundation to provide autofill service the information about the
start and end of IME animation. This will help autofill to make
informed results to hold up animating Bottomsheet till the IME
animation completes.

This change only handles insets generated on the client side.

Test: atest WmTests:WindowManagerServiceTests
      Manually verify autofill logs on recieving animation updates.
Flag: android.service.autofill.improve_fill_dialog_aconfig
Bug: 390528373
Change-Id: I00965976cd4fd62faf95de4720584273a18faea3