Show breadcrumbs section as a graph visualization

[kevinschaper]

Our breadcrumbs section is the rare lucky circumstance where the number of nodes & edges of a graph would actually be attractive to visualize - so we should move from using text to actually displaying the history as a graph.

Secondarily, depending on the practicality, we could keep the breadcrumbs/history going between searches or views of disconnected components and just display them as disconnected graphs on the same panel.