Send update config change when letterbox is moved

When letterbox is repositioned, window configuration bounds are changed.
Because we currently only report public config changes in
diffPublicOnly, the client doesn't report changes in window
configuration.

We should always report window configuration bounds change to notify
that the position of window has changed.

Bug: 262900133
Test: atest FrameworksCoreTests:android.app.activity.ActivityThreadTest
      Manual test with app in bug
Change-Id: I9fc10876c03933ac8aac05205d56ad6537df72a8