Update drag-and-drop to support resizeable widgets

We updated the hit-detection to consider if the dragging item contains the center of any other item, instead of the other way around. We also keep track of the previous target item to prevent rapidly oscillating between two items.

Bug: 368056271
Test: UI update, manually on the device by dragging items of different
sizes
Flag: com.android.systemui.communal_widget_resizing

Change-Id: Ibf0c24cfde7a098d305443dd79c729d098ecbc42