ssh kitten: Passthrough to ssh if run outside of kitty

Also, ensure that the ssh data request is only served if it is received
over the tty of the correct kitty window.

shell-integration/ssh/bootstrap.py

@@ -59,7 +59,8 @@ def dcs_to_kitty(type, payload):
 
 def send_data_request():
     hostname = os.environ.get('HOSTNAME') or os.uname().nodename
-    write_all(tty_fd, dcs_to_kitty('ssh', 'hostname={}:pwfile=PASSWORD_FILENAME:user={}:pw=DATA_PASSWORD'.format(hostname, getpass.getuser())))
+    write_all(tty_fd, dcs_to_kitty(
+        'ssh', 'id=REQUEST_ID:hostname={}:pwfile=PASSWORD_FILENAME:user={}:pw=DATA_PASSWORD'.format(hostname, getpass.getuser())))
 
 
 def debug(msg):