Fix handling of complex embedded args

If pulling from argv, it has already been
shell split. Use shlex to join to correctly
requote anything that needs quoting.

confluent_client/bin/confetty

@@ -912,7 +912,7 @@ def main():
         do_command("start /nodes/%s/console/session" % session_node, netserver)
         doexit = True
     elif shellargs:
-        command = " ".join(shellargs)
+        command = shlex.join(shellargs)
         do_command(command, netserver)
         quitconfetty(fullexit=True, fixterm=False)