feat!: change gestures to look at selected when dragging (#7991)

* feat: change gestures to look at selected when dragging

* chore: fix tests

* chore: format

* chore: PR comments

core/interfaces/i_selectable.ts

@@ -6,12 +6,16 @@
 
 // Former goog.module ID: Blockly.ISelectable
 
+import type {Workspace} from '../workspace.js';
+
 /**
  * The interface for an object that is selectable.
  */
 export interface ISelectable {
   id: string;
 
+  workspace: Workspace;
+
   /** Select this.  Highlight it visually. */
   select(): void;
 
@@ -23,6 +27,7 @@ export interface ISelectable {
 export function isSelectable(obj: Object): obj is ISelectable {
   return (
     typeof (obj as any).id === 'string' &&
+    (obj as any).workspace !== undefined &&
     (obj as any).select !== undefined &&
     (obj as any).unselect !== undefined
   );