Generalize support for 'App Info', 'Uninstall' and 'Delete'

This allows other DragSource's to allow this behaviour, instead of it being
tied to specific source types.

Change-Id: I06b7c39b1b34a0ae141245bcc13b6a0873a4c0fd

src/com/android/launcher3/Workspace.java

@@ -4212,6 +4212,16 @@ public class Workspace extends SmoothPagedView
         return true;
     }
 
+    @Override
+    public boolean supportsAppInfoDropTarget() {
+        return false;
+    }
+
+    @Override
+    public boolean supportsDeleteDropTarget() {
+        return true;
+    }
+
     @Override
     public void onFlingToDelete(DragObject d, int x, int y, PointF vec) {
         // Do nothing