HostServ: ident@host vhosts (CHGIDENT)

A vhost may be ident@host, not just host: apply_vhost splits it and sends
CHGIDENT for the ident plus CHGHOST for the host. valid_vhost validates
the optional ident part; ON/SET/ACTIVATE/identify all route through
apply_vhost, so a bare host still works unchanged. New SetIdent action.

hostserv/src/set.rs

@@ -21,7 +21,7 @@ pub fn handle(me: &str, from: &Sender, args: &[&str], ctx: &mut ServiceCtx, net:
     match db.set_vhost(account, host, from.nick) {
         Ok(()) => {
             for uid in net.uids_logged_into(account) {
-                ctx.set_host(&uid, host);
+                ctx.apply_vhost(&uid, host);
             }
             ctx.notice(me, from.uid, format!("Vhost \x02{host}\x02 assigned to \x02{account}\x02."));
         }