Workspace information should be pulled from the VS code plugin

## Describe it

I already have workspace selected in the VS code plugin. However, the notebook still asks me to punch in the subscription, RG, WS details. I would be good to pull the information from the plugin.

## Additional context

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The issue mentions the VS Code plugin and an Azure Machine Learning notebook, but no files or tests. Start by tracing how the notebook currently requests subscription, resource group, and workspace details and how the plugin exposes the selected workspace. Done means the notebook uses the plugin's selected workspace instead of prompting for those values.

Written by the indexing model from the issue text.