tools/mpremote: Allow terminator for shortcut commands.

For example, the `reset` shortcut previously allowed an optional delay, but
the argument handling cannot handle `reset next-command` as `next-command`
will be interpreted as the delay argument.  The fix in this commit allows
`reset + next-command`.

This work was funded through GitHub Sponsors.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

tools/mpremote/mpremote/main.py

@@ -406,6 +406,8 @@ def usage_error(cmd, exp_args, msg):
         cmd = args.pop(0)
         exp_args, exp_sub, _ = _command_expansions[cmd]
         for exp_arg in exp_args:
+            if args and args[0] == "+":
+                break
             exp_arg_name = exp_arg[0]
             if args and "=" not in args[0]:
                 # Argument given without a name.