Make sure setting switch bar state is announced.

When the switch is clicked, a TYPE_VIEW_CLICKED a11y
event is produced. It works fine if the switch bar is
clicked, but if the switch itself is clicked the event
comes from the switch, which is marked as not important
for accessibility. Re-dispatching events from the switch
as coming from the switch bar makes sure that the event
comes from a view that accessibility services can see.

Bug: 30484493
Change-Id: Ie48cc78594c64b1cc5735475e1cb5959fadaaf4a