gow -g expects script arguments when they are not required

gow -g is requiring that a command argument be passed, even if the script being called does not need them. Passing an empty argument seems to work around this, but it is not intuitive.

Example:

% cat script.sh
#!/bin/bash
echo "hello world"

% gow -g ./script.sh
"gow" is the missing watch mode for the "go" command.
Runs an arbitrary "go" subcommand, watches files, and restarts on changes.

Usage:

	gow <gow_flags> <cmd> <cmd_flags> <cmd_args ...>
...

% gow -g ./script.sh ""
hello world

Reproduce the issue with the commands shown in the report: gow -g ./script.sh and the workaround using an empty argument. Start at the CLI argument parsing and command execution entry points, then verify that a script requiring no arguments runs without the empty argument while existing command arguments still work.