Enable docstrings/intellisense for custom libraries in notebooks

[Thomas_Fosterbi]

Currently docstrings/intellisense do not work for custom libraries in fabric notebooks. 

This has been confirmed as a feature gap and is on the backlog 

https://www.reddit.com/r/MicrosoftFabric/s/G0irMOtdrC

Vote for this idea to bring a feature to fabric that will be celebrating it's 30th anniversary in visual studio this year!