a go rewrite of @defparam's smuggler.py
this is very imperfect and was mostly vibe coding and learning for fun but still kinda works.
only http1 smuggling supported. will not be maintained
-u/--url domain
-v/--vhost virtual_host
-m/--method HTTP_method
-q/--quiet
-t/--timeout request_timeout
--no-color
-x proxy