SSH Remoting: Fix reconnects (#19485)

Before this change messages could be lost on reconnect, now they will
not be.

Release Notes:

- SSH Remoting: make reconnects smoother

---------

Co-authored-by: Nathan <nathan@zed.dev>

crates/proto/src/macros.rs

@@ -32,6 +32,7 @@ macro_rules! messages {
                         responding_to,
                         original_sender_id,
                         payload: Some(envelope::Payload::$name(self)),
+                        ack_id: None,
                     }
                 }