revamp archive coverage page to list instances of mentioned listers

Now that we are increasing archive coverage quite a bit, the archive coverage page is starting to show some limits. In particular, we need a structured way to list the various instances of supported listers.

as a first approximation we can make the tooltip of each listed logo include a list of instances — this would work for now, but it won't scale for much, because there is only so much usable space in a tooltip
alternatively we can make each logo link to a dedicated //page//, where we list all deployed instances of the lister (which will probably mean solve #1266 as a prerequisite)
alternatively, don't know, a way in between maybe? e.g. a box that opens when clicking on each logo, with a proper
with links to each instance?
A proper solution (#1266) would require some work, but the current state is no longer good enough in terms of clarity of what we currently archive… Thoughts?

Migrated from T1870 (view on Phabricator)