BUG/MEDIUM: servers: Store the connection hash with the parameter cache

BUG/MEDIUM: servers: Store the connection hash with the parameter cache

When we store the negociated server parameters, such as the ALPN, also
store the calculated hash with the connection. If it is different, as
can happen because the IP address is different because set-dst was used,
we certainly do not want to reuse the information in the cache,
otherwise we could end up using the wrong ALPN and mux.
That means we already have to calculate the hash in connect_server()
now, while before we would not do it for Websockets, if we could not do
connection reuse, as that's all the hash was used for.

This should fix Github issue #3386

This should be backported as far as 3.2.