Allow reordering of linked subgraph widgets (#5981)

Widgets which are promoted by linking to a subgraphInput node are now
also displayed in the subgraph configuration window. They can now be
reordered by drag and drop along with proxyWidgets


![linked-reorder](https://github.com/user-attachments/assets/e1b8d590-211a-4d84-9f84-3a5fd5a7aa6c)

Known Issues:
- "Hide All" will incorrectly remove physically linked widgets

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5981-Allow-reordering-of-linked-subgraph-widgets-2866d73d365081d9b27cf4a9c3078007)
by [Unito](https://www.unito.io)

tests-ui/tests/widgets/proxyWidget.test.ts

@@ -1,11 +1,9 @@
 import { describe, expect, test, vi } from 'vitest'
 
 import { registerProxyWidgets } from '@/core/graph/subgraph/proxyWidget'
-import {
-  type LGraphCanvas,
-  LGraphNode,
-  type SubgraphNode
-} from '@/lib/litegraph/src/litegraph'
+import { parseProxyWidgets } from '@/core/schemas/proxyWidget'
+import { LGraphNode } from '@/lib/litegraph/src/litegraph'
+import type { LGraphCanvas, SubgraphNode } from '@/lib/litegraph/src/litegraph'
 
 import {
   createTestSubgraph,
@@ -66,14 +64,19 @@ describe('Subgraph proxyWidgets', () => {
       subgraphNode.widgets[1].name
     )
   })
-  test('Will not modify existing widgets', () => {
+  test('Will serialize existing widgets', () => {
     const [subgraphNode, innerNodes] = setupSubgraph(1)
-    innerNodes[0].addWidget('text', 'stringWidget', 'value', () => {})
+    innerNodes[0].addWidget('text', 'istringWidget', 'value', () => {})
     subgraphNode.addWidget('text', 'stringWidget', 'value', () => {})
-    subgraphNode.properties.proxyWidgets = [['1', 'stringWidget']]
+
+    const proxyWidgets = parseProxyWidgets(subgraphNode.properties.proxyWidgets)
+    proxyWidgets.push(['1', 'istringWidget'])
+    subgraphNode.properties.proxyWidgets = proxyWidgets
+
     expect(subgraphNode.widgets.length).toBe(2)
-    subgraphNode.properties.proxyWidgets = []
-    expect(subgraphNode.widgets.length).toBe(1)
+    expect(subgraphNode.widgets[0].name).toBe('stringWidget')
+    subgraphNode.properties.proxyWidgets = [proxyWidgets[1], proxyWidgets[0]]
+    expect(subgraphNode.widgets[0].name).toBe('1: istringWidget')
   })
   test('Will mirror changes to value', () => {
     const [subgraphNode, innerNodes] = setupSubgraph(1)