Makes the litegraph `node.widgets` array `shallowReactive` and makes the
`nodeData.widgets` a `reactiveComputed` derived from the litegraph
widget data.
Making changes to the structure of litegraph items is somewhat
dangerous, but code search verifies that there are no custom nodes using
`defineProperty` on `node.widgets`
This fixes display of promoted widgets on subgraph node and any custom
nodes that dynamically add or remove widgets.
TODO:
- Investigate occasional dropped widgets.
- Some of this was confusion with `canvasOnly` widgets and widgets not
implemented in vue. Will keep investigating, but I'm not terribly
concerned with actual test cases and it being an objective improvement.
Known Issue:
- Node does not grow/shrink to fit changed widgets
┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6019-Make-nodeData-widgets-reactive-2896d73d3650815691b6ee370a86a22c)
by [Unito](https://www.unito.io)
