Further subgraph improvements (#6466)

- Prune disconnected widgets on config panel open
- Fix breakage of DOMWidgets on double nest
- Fix self clipping of proxied DOMWidget nodes
- Blacklist cloning of promtoed widget prop

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6466-Further-subgraph-improvements-29c6d73d365081c8b63dda068486805c)
by [Unito](https://www.unito.io)

src/core/graph/subgraph/proxyWidgetUtils.ts

@@ -1,5 +1,9 @@
 import { parseProxyWidgets } from '@/core/schemas/proxyWidget'
 import type { ProxyWidgetsProperty } from '@/core/schemas/proxyWidget'
+import {
+  isProxyWidget,
+  isDisconnectedWidget
+} from '@/core/graph/subgraph/proxyWidget'
 import { t } from '@/i18n'
 import type {
   IContextMenuValue,
@@ -163,3 +167,10 @@ export function promoteRecommendedWidgets(subgraphNode: SubgraphNode) {
   subgraphNode.properties.proxyWidgets = proxyWidgets
   subgraphNode.computeSize(subgraphNode.size)
 }
+
+export function pruneDisconnected(subgraphNode: SubgraphNode) {
+  subgraphNode.properties.proxyWidgets = subgraphNode.widgets
+    .filter(isProxyWidget)
+    .filter((w) => !isDisconnectedWidget(w))
+    .map((w) => [w._overlay.nodeId, w._overlay.widgetName])
+}