Update worker and 3D viewer

[trungleduc]

Code changes:

Update JCAD format:

• new outputs field with the following schema

    "outputs": {
      "type": "object",
      "additionalProperties": false,
      "patternProperties": {
        "^.*$": {
          "type": "string"
        }
      }

This field contains the output of the post-processing operator. The 3D viewer uses this field to render the shapes without re-run all post-processing operators at startup,

• New part type Post::Operator with the following schema:

{
  "type": "object",
  "description": "Post::Operator",
  "title": "IPostOperator",
  "required": ["Object"],
  "additionalProperties": true,
  "properties": {
    "Object": {
      "type": "string",
      "description": "The name of input object"
    }
  }
}

This is a base part for all post-processing operators, the extensions need to extend this schema with the part prefixed with Post:: to be picked by JupyterCad

New tokens

• IJCadFormSchemaRegistryToken: token allowing extension to register new form schema, this helps create parameter form and dialog.
• IJCadExternalCommandRegistryToken: token allowing extension to add buttons to the JupyterCad toolbar

New worker system

• IJCadWorkerRegistryToken token now exposes a default worker using occ-worker and allows registering more workers for the post-processing operator.
• An external worker needs to implement the IJCadWorker interface.
• On creation, the 3D viewer will register its message handlers with the default worker and all external workers.

New rendering routine:

• On startup, the 3D viewer will send a WorkerAction.LOAD_FILE message to the default worker, the default worker then returns the parsed OCC shapes with the same flag. The viewer will render the OCC shapes and use data from outputs field of the shared model to render the post-processing operators.
• On object change, the 3D viewer will send a WorkerAction.LOAD_FILE message to the default worker and get back the parsed OCC shapes and also the BREP strings of objects required in the post-processing operator.
• These BREP strings will be sent to the registered workers with the WorkerAction.POSTPROCESS message. Once the workers finish processing data, they send back to the 3D view the STL string of processed shapes with the MainAction.DISPLAY_POST message.
• The STL strings of processed shapes are saved into the outputs field of the shared model.

closes #236

[github-actions]

👈 Launch a Binder on branch trungleduc/jupytercad/worker-support

[martinRenou]

Out of curiosity, what is this and why is it needed?

[trungleduc]

I had an issue with building the Salome extension because of missing interfaces in opencascade.js so I tried to remove the opencascade.js dependency since we only need the init function.
It turned out the problem was a missing typescript config in the Salome extension, we can roll back to using the function provided by opencascade.js

[martinRenou]

We may want to provide a way to clean outputs in the future?

[trungleduc]

indeed, adding it now, the output needs to be deleted when the operator is removed

[martinRenou]

Thanks!