Tkakar/fix 515

[tkakar]

• Fixes Investigate errors in Neuroglancer notebook #514 Fix nested data URLs - corrupted when shared via VitessceConfig.web_app() #515 the data url created by that was throwing errors downstream in tissue-map-tools.
• Updates vitessce-js version.
• The old Neuroglancer notebook was deleted as the latest updates (layers addition, etc.) do not support it.

Notes regarding #514

• Every time a Neuroglancer notebook has to be executed, the kernel needs to be restarted, better a new browser tab/window is used. That's why the existing `` notebook was separated into two.
• For the worker thread related errors, issue Fix Issues in neuroglancer-with-segments notebook when widget() is used. #517 was created.
• Currently, to avoid the above issues, only vc.web_app() is provided in these notebooks.