revert: "refactor: Remove block and workspace drag surfaces (#6758)" (#6888)

This reverts commit 332c0fd2f2.

core/workspace_dragger.ts

@@ -20,6 +20,9 @@ import type {WorkspaceSvg} from './workspace_svg.js';
 /**
  * Class for a workspace dragger.  It moves the workspace around when it is
  * being dragged by a mouse or touch.
+ * Note that the workspace itself manages whether or not it has a drag surface
+ * and how to do translations based on that.  This simply passes the right
+ * commands based on events.
  */
 export class WorkspaceDragger {
   private readonly horizontalScrollEnabled_: boolean;
@@ -62,6 +65,7 @@ export class WorkspaceDragger {
     if (common.getSelected()) {
       common.getSelected()!.unselect();
     }
+    this.workspace.setupDragSurface();
   }
 
   /**
@@ -74,6 +78,7 @@ export class WorkspaceDragger {
   endDrag(currentDragDeltaXY: Coordinate) {
     // Make sure everything is up to date.
     this.drag(currentDragDeltaXY);
+    this.workspace.resetDragSurface();
   }
 
   /**