feat: add dragging hand when moving node

Author: Diede Kerkhof

frank-flow/src/frontend/src/app/flow/node/node.component.scss

@@ -14,6 +14,10 @@
     cursor: grab;
   }
 
+  &:active {
+    cursor: grabbing;
+  }
+
   &.isActive {
     background: var(--accent-lighter-10);
     border: 3px solid var(--accent-darker-1);