Don't send configuration updates to apps that are going-away

Specifically, this adds checks for isVisibleRequested == false and
avoids sending new configs or other events. If an app is going to
be hidden, usually it means we're in an animation and don't want
it to relayout.

Bug: 179270750
Test: existing tests pass and phone behavior remains unchanged.
Change-Id: I8e8e21fcd3b8f4ff0f9b22d04c1abb908e719422