The UID introduction omitted the second user field (insp sends both a real and a
displayed user), and the parser didn't strip IRCv3 message-tag prefixes, so
tagged PRIVMSGs addressed to a service were dropped. With both fixed a service
links to a real insp4 uplink and answers commands. Adds an irctest services
controller so this is verified against an isolated, throwaway ircd.
