Tracking: integrate with usage of nss-resolve

[mathstuf]

Fedora 33 released and now uses systemd-resolved for its DNS lookups from glibc's level. This means that the resolv.conf approach is not as useful anymore. I have modified /etc/nsswitch.conf to avoid nss-resolve for now, but this is not a long-term solution. I've started a discussion on Ask Fedora, but would like to let developers here be aware of it in case there's something that can be done here too.

I suspect we'll need something from systemd to support network namespaces better, but I don't know.

[slingamn]

As a band-aid, it should be possible to bind-mount over /etc/nsswitch.conf as well (just creating, e.g., /etc/netns/protected/nsswitch.conf with a hosts line that doesn't use systemd-resolved). I'll test this approach.