Draggable and Deleteable

[d-sooter]

It would be really cool to be able to set some nodes as Draggable = false and Deletable = false in order to be able to lock specifc nodes (like an input node). I know React flow supports it so i cant image that it would be so hard. Im happy to create a PR to implement it but would love just to get a direction as to where i can implment it and save time searching.

My idea would be to implement it two steps.

1. Allow setting the those values via graph json

"nodes": [
    {
      "id": "d55648c2-7d7c-48aa-8d8c-bfa04c7c1bef",
      "name": "request",
      "position": {
        "x": 0,
        "y": 0
      },
	  "draggable": false,
	  "deletable":false,
      "type": "inputNode"
    },

2. Consider adding it to the node context menu (not sure if this is the right idea)

Thanks in advance