Refreshed BIP324

On February 19th, 2023, Anthony Towns shared his opinion on the negotiation process of short ids in Bitcoin development. He suggested two negotiation steps, one to share information about the tables used, and the other to choose a mutually recognized table and specify any additions. Pieter Wuille agreed with this but mentioned that if all negotiation of the mapping table happens just once before VERACK, then there is no need for re-negotiating short commands after they are already in use. However, the negotiation process currently involves sending a VERSION message, seeing what their VERSION message is, announcing features depending on the version, sending the VERACK, waiting for their announcements and VERACK, and then the negotiation is finished. Adding an extra phase either just before or just after the VERACK could solve the issue of having only two steps in the negotiation process. Choosing one's own short id mapping from day 0 would mean that every bip324 node could use a single short id mapping for all outgoing messages, which might also make implementation marginally easier.