Notebook to illustrate what speed-ups we automatically do in the background. #59

Currently, @Sonja-Stockhaus is implementing that for raster-images, spatialdata-plot automatically chooses an appropriate scale for multi-scale images or downscales overly large images. Next, we're going to use datashader to pre-render layers with f.e. 300 million points. This serves the purpose of massively speeding up quick default plots.

Since this involves quite some logic in the background that a given user should have knowledge and control over, we should provide a notebook that explains and shows these improvements, potentially including a tiny bit on how much faster that makes a plot.

The notebook should illustrate the following cases (pre datashader):

• The default behaviour
• What are my options and knobs to turn for single-scale-images?
• What are my options and knobs to turn for multi-scale-images?