Runs the router certificate fingerprint validation for router control-channel
underlay types, which was previously skipped for any connection carrying a
channel type header. Connections of other types (e.g. the raft mesh) continue to
be deferred to their own acceptor.
The already-connected / churn guard is applied only when establishing a new
channel, so additional underlays of a grouped control channel are not rejected
while the router is already connected.
Paul Lorenz
abf9cf8b1b