Make a ScriptedForms extension builder

[SimonBiggs]

Refactor ScriptedForms as a JupyterLab App. Have it boot the same way as JupyterLab does allowing it to make use of installed JupyterLab extensions.

Split out section and variable types each into their own JupyterLab extensions.

Create a "debug mode" within ScriptedForms which opens up the python kernel console and creates a "snack bar" message when errors occur. It would also open up a text editor to edit the form.

Also create an "extension builder mode". Have the ability for users to make their own variable types and section types. And then optionally upload them to npm. It would open a typescript text editor, as well as an html, and CSS editor. It would be prefilled with a hello world version of a section or variable type.

The extensions would be loaded up in a custom "live compile" mode, which means without page reload the extension can be used. Whenever the extension code files change just the instances of that component will reload.