Fix hub in edit mode overlapping with display cutout

In hub edit mode, calculate paddings for the responsive grid based on
toolbar height, window insets and orientation.
Also center the widgets in window.

Bug: 404273900
Test: on mobile and tablet
Flag: com.android.systemui.communal_responsive_grid
Change-Id: Ie7510fc8163cf1ff3afbfadfa17dac05a8a4213b