Start page > open sample notebook is broken

On WIP/NoDS in vscode-python we are still executing python.datascience.opennotebook to open the sample notebook, which of course has been renamed to jupyter.opennotebook. Two ideas to solve this:

1. Update it to execute jupyter.opennotebook, problem is if Jupyter extension is not installed this would be a noop. Solution to that would be to display a prompt at this juncture telling the user that they need the Jupyter extension to open the sample notebook.
2. Instead of the Python extension directly executing the command, add an extensibility point to the API. However we would still need to check for whether the jupyter extension is installed at this juncture I believe.

Other approaches/suggestions/thoughts here? @DonJayamanne @rchiodo @ianmatthewhuff @davidkutu

[DonJayamanne]

Another possible idea:

• We just ship Jupyter as a dependency of Python extension.

[rchiodo]

Another possible idea:

• Keep the command. Command handler checks for jupyter extension. If there, runs the other command, if not, asks user to install it.