Prevent partial copy of custom widgets when performing linked promotion on subgraphs (#6079)

The `toConcrete` call creates a restricted view of a widget that extends
from `BaseWidget`. A copy of the widget created by `createCopyForNode`
will also inherit this restricted view. This creates two problems
- Some widget properties (like `displayValue`) have been judged unsafe
and are explicitly blacklisted from being copied
- The widget now extends from `BaseWidget`. This results in the widget
being processed differently in some logic, such as `#processWidgetClick`
- Because `LegacyWidget` provides an implementation for `onClick`, the
presence of click handlers can not be used to determine which should be
used.

As a proposed, minimal workaround. Widgets which do not already extend
from BaseWidget are no longer cloned through `createCopyForNode`.

Because this PR involves side-stepping properties which have been
explicitly blacklisted. I'd recommend waiting to merge/backport until
after the release of 1.28.7

Resolves Kosinkadink/ComfyUI-VideoHelperSuite#569

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6079-Prevent-partial-copy-of-custom-widgets-when-performing-linked-promotion-on-subgraphs-28d6d73d36508198950efd401186ddef)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Alexander Brown <drjkl@comfy.org>
Co-authored-by: GitHub Action <action@github.com>

src/lib/litegraph/src/subgraph/SubgraphNode.ts

@@ -28,8 +28,8 @@ import type {
 } from '@/lib/litegraph/src/types/serialisation'
 import type { IBaseWidget } from '@/lib/litegraph/src/types/widgets'
 import type { UUID } from '@/lib/litegraph/src/utils/uuid'
+import { BaseWidget } from '@/lib/litegraph/src/widgets/BaseWidget'
 import { AssetWidget } from '@/lib/litegraph/src/widgets/AssetWidget'
-import { toConcreteWidget } from '@/lib/litegraph/src/widgets/widgetMap'
 
 import { ExecutableNodeDTO } from './ExecutableNodeDTO'
 import type { ExecutableLGraphNode, ExecutionId } from './ExecutableNodeDTO'
@@ -331,9 +331,10 @@ export class SubgraphNode extends LGraphNode implements BaseLGraph {
     inputWidget: IWidgetLocator | undefined
   ) {
     // Use the first matching widget
-    const promotedWidget = toConcreteWidget(widget, this).createCopyForNode(
-      this
-    )
+    const promotedWidget =
+      widget instanceof BaseWidget
+        ? widget.createCopyForNode(this)
+        : { ...widget, node: this }
     if (widget instanceof AssetWidget)
       promotedWidget.options.nodeType ??= widget.node.type