Add a new output format "oneline" for "show quic" command. This prints
one connection per line with minimal information. The objective is to
have an equivalent of the netstat/ss tools with just enough information
to quickly find connection which are misbehaving.
A legend is printed on the first line to describe the field columns
starting with a dash character.
This should be backported up to 2.7.
2273af11e0