Calculate and store widget parent id and position when the interfaces are rendered

This removes the need to calculate widget bounds and parent on demand by
traversing up the widget tree.

runelite-api/src/main/java/net/runelite/api/Client.java

@@ -412,15 +412,6 @@ public interface Client extends GameEngine
 	 */
 	Widget getWidget(WidgetInfo widget);
 
-	/**
-	 * Gets an array of widgets that correspond to the passed group ID.
-	 *
-	 * @param groupId the group ID
-	 * @return the widget group
-	 * @see net.runelite.api.widgets.WidgetID
-	 */
-	Widget[] getGroup(int groupId);
-
 	/**
 	 * Gets a widget by its raw group ID and child ID.
 	 * <p>