feat: help message in pwar_cli

[umbertov]

Make the CLI fail on unexpected arguments/typos, and print a helpful message like this:

invalid option: --help
usage: build/linux/pwar_cli OPTIONS
Available options:
	-ip,	 --ip	 NUMBER
	-p,	  --port	 NUMBER
	-pt,	 --passthrough_test
	-b,	  --buffer_size	 NUMBER
	--oneshot