Add DNS Resolver status page
We can fetch some useful status data from unbound using
unbound-control -c /var/unbound/unbound.conf <command>, and it would be nice to show some of that to users if we can find a clean way to format it.
At a minimum,
dump_infra output should be there so users can have visibility of the internal tracking stats unbound is using about upstream DNS servers. In resolver mode, it lists the roots, in forwarding mode it lists the forwarding servers.
We could also have a page to show the output of
dump_cache but that may need some special handling due to its potential size in a busy environment.
There is also some interesting info in
stats_noreset but we'd need to pick and choose what to show to avoid information overload.
dump_infra will be empty if there have been no DNS queries recently. There are some cases where
unbound-control fails to run that still need investigation.
Setting to 2.4.4 for now, but can be moved forward if there is no time for it.