* Log when starting letsencrypt endpoint + clearer errors
Running `gotosocial server` with the default configuration will try to
bind to :80 and listen for letsencrypt challenges, which will fail if
running as non-root (w/o capabilities), or if eg. nginx hogs the port.
When that happens, this should make it more obvious what's wrong.
* Log what address/port we're listening on
Always nice not to have to guess. Also feels more consistent than just
doing it for the letsencrypt endpoint.
86e8e7fd21