Add tool for visualizing crate hierarchy (#3315)

* Add tool for visualizing crate hierarchy

* Update crate structure

* Restructure crate viz and integrate crate into workspace

* Remove transitive dependency edges

* Move png / svg creation into the rust binary

.nix/flake.nix

@@ -98,6 +98,9 @@
             pkgs.gnuplot
             pkgs.samply
             pkgs.cargo-flamegraph
+
+            # Plotting tools
+            pkgs.graphviz
           ];
           all = desktop ++ frontend ++ dev;
         };