Pass Task configuration changed for all TaskFragments at once

Before, we passed Task configuration changed for every embedded
TaskFragment. Now, we only passed one Task configuration changed for the
whole Task. The organizer will then update TaskFragments in the Task
accordingly.

Bug: 240519866
Test: atest WmTests:TaskFragmentOrganizerControllerTest
Change-Id: I755c11a1bcee0dd0305a090b229e867b79eee46d