lib-smtp: smtp-params - Assume all capabilities are supported when adding parameter...

lib-smtp: smtp-params - Assume all capabilities are supported when adding parameter event fields.

The actual capabilities are not really needed, since any assigned field is
relevent for event processing, whether the remote end will accept it or not.

This also fixes an assert failure occuring for proxied connections. Since the
server and client (proxy) connections can have different capabilities and since
the client connection does not have a proper capability list available in the
beginning of the handshake, the event created for a client transaction would
cause an assert failure when parameters were assigned that did not match the
capabilities (none).