Adopt JupyterServerProvider API to simplify connection workflow

[gjsjohnmurray]

microsoft/vscode-jupyter#13894

[DonJayamanne]

Thanks @gjsjohnmurray
I was planning on creating an issue in here, but you beat me to it, thanks
I'm one of the engineers working on VS Code, and the above API should in theory make it unnecessary for users to have to manually enter the server information.

Your extension could utilize the API and contribute a server named InterSystems IRIS or the like .
Here are some samples for the usage of this API

• https://github.com/microsoft/vscode-extension-samples/tree/main/jupyter-server-provider-sample
• https://github.com/microsoft/vscode-jupyter-hub

Basically all of this would be unnecessary:

* In the quickpick titled "Select Kernel" choose Existing Jupyter Server....  
* In the next quickpick ("Select a Jupyter Server") choose Enter the URL of the running Jupyter server.  
* Enter http://localhost:50773/servername:namespace?token=1 when prompted. Replace servername with the name of the ( Server Manager definition you previously created. Replace namespace with the target namespace on that server. Do not omit the colon between these two elements. For example http://localhost:50773/iris231:USER?token=1  
* On the next prompt ("Change Server Display Name") enter a suitable name, for example IRIS231 USER. Don't leave this blank, else the display name will default to localhost, meaning you won't be able to distinguish between entries you create for different servername:namespace combinations.

[DonJayamanne]

@gjsjohnmurray wanted to reach out to you about a proposed API that will make it unnecessary to create a fake jupyter server.
Today I can see that you have a fake server that handles http requests and the like,
Its possible (via a proposed API) to contribute a jupyter server that doesn't listen to any HTTP endpoints.
I.e. you can intercept all of the messages (http calls are made using a fetch implementation that can be provided by 3rd party and similarly websocket class implementation too can be provided by 3rd party, which means http requests completely unecessary.

Let me know if this is something you'd like to implement and I can led a hand.
Here's the proposed API that makes all of this possible https://github.com/microsoft/vscode-jupyter/blob/main/src/api.proposed.jupyterSettings.d.ts