Support shapes

[jo-mueller]

This adds support for the napari shapes layer, adds a demo notebook as well as a corresponding test.

[haesleinhuepf]

Hi @jo-mueller ,

in the notebook is a warning saying:

napari.manifest -> 'napari-vedo-bridge' could not be imported: The name field in the manifest ('napari-clusters-plotter') must match the package name ('napari-vedo-bridge')

Is this something to be worried about?

Best,
Robert