Widget to explain Color code of shapes #350

Hi,

I would love to replace Xenium explorer with Napari-Spatialdata now that Shapes performance is super good.

What has been stopping me is that it is at the moment really difficult to understand color coding for shapes, which is something I constantly use.

As this is currently not supported by Napari napari/napari#7306 my current work around would be to define colors manually in .uns and have a matplotlib plot in Juypter that shows what color means what.

Would it maybe be possible to have this as a automatic Napari widget? Read colors .uns and create a little legend?