Visualize Self Backing (recursive backing)

[Spenhouet]

Currently, the list of underlying assets does not list the asset itself, if it is somehow used as backing itself. Having such a self-backing is a risk and we should try to visualize that. We should make sure that in case, the list of underlying assets and the list of derivatives also lists the asset itself. At some position we should show a warning that this asset also has self backing which is not included in the shown stats and the Sankey diagram.