Add support for cookies in response

[vearutop]

Similar to having header field tags in output structure, we can have cookie. However, cookies have more additional parameters that perhaps can be configured as field tag options, e.g. cookie="foo,httponly,path=/foo".

[reyesdiego]

Yes.. thank you for adding this issue. I think the idea would be to work on the encoder and collector files right? I'm not that expert with golang