Consider integrating VM topography visualization tool

[andrewdavidwong]

Several users over the years have requested a feature that allows them to visualize the topography of their VMs in the form of a graph, and some of our users have even developed tools that accomplish these. We should consider selecting and integrating one of these tools into Qubes.

Discussion threads:

• https://groups.google.com/d/topic/qubes-users/EPuXNkSFxdE/discussion
• https://groups.google.com/d/topic/qubes-devel/64-WJIMY18A/discussion

@Zrubi's implementation: https://gist.github.com/Zrubi/6229d5400bde987b1aa8da516553b909

On the community-developed feature tracker:
https://www.qubes-os.org/qubes-issues/#vm-topography-visualization-tool