Add flag to support adding cookies

[marcelo321]

Please describe your feature request:

Add a flag so we can add cookies to the requests, -cookies. or -b as curl does.

Describe the use case of this feature:

Can be used to test authenticated issues and other things.

[ehsandeep]

@marcelo321 how this is different from adding cookies using -H, -header flag?

   -H, -header string[]          custom http headers to send with request