Change similarity heatmap to stained glass plot

[heringerp]

Basically remove half of the heatmap as it is redundant to look similar to StainedGlass plots, this should also reduce the load on the html (only slightly).

[heringerp]

Something like this:

However, the implementation of this might take some time, since there is no vega-lite plot directly corresponding to this, so more code is necessary. Idea: rotate "rect" marks (correct sizing might be an issue) and place them on an x-y-Grid (grid coordinates might need to be pre-calculated in Rust code).

[danydoerr]

The real added value is that there is space to plot draw a dendrogram of a hierarchical clustering of the samples. I guess this will also be rather custom. This whole issue might be a little lab student project on its own.

[heringerp]

Yes, displaying a dendrogram requires even more custom code and also some changes on the Rust side to include that information in what is stored in the HTML (currently the HTML file only knows the ordering and nothing about the hierarchy of the clustering).