Forward selection UI events to ActorFormFillingService.

This change implements the AutofillSelectionDialogEventHandler methods
in AttemptFormFilingTool by forwarding to new methods on the
ActorFormFillingService. The new methods are left unimplemented.

Bug: b:483405648
Change-Id: Iae6e42692654a4eb30555ef20777b69f574d7a0e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7583120
Reviewed-by: Jihad Hanna <jihadghanna@google.com>
Reviewed-by: Kevin McNee <mcnee@chromium.org>
Commit-Queue: Slobodan Pejic <slobodan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1588696}