Beta3 of F# Jupyter Notebooks

Updated Paket & Paket.Core to strictly target 5.142.0 (this is to handle the deprecation of TLS 1.0 & 1.1)
Many updated dependencies FCS, FSharp.Core
Clearer error messages on missing Jupyter
Initial helpers for FsLab
Update cell status on using #N
Reduced MSBuild dependency, easier builds on MacOS and Linux