Native Notebooks - Jupyter Server Selector

[ayim]

The Jupyter Server entry point that used to be located here:

Will be moved to the global status bar in Native Notebooks since the original entry point is no longer available.

All functionality should remain the same - this will help achieve experience parity in native notebooks.

[DonJayamanne]

Thanks for filing this issue with the suggestions, I'm closing this in favor of #254
The functionality & UI elements will be addressed in that issue.