Respect response's Set-Cookie header on HTTP::Response#next-request

[astj]

Currently, HTTP::Response#next-request doesn't care about Set-Cookie header of the response (understand just Location header).
So, If someone wants to request with some received Cookie (like session Cookie), one has to set Cookie manually like following:

    my $next-req = $res.next-request;
    my $cookies = HTTP::Cookies.new;
    $cookies.extract-cookies($res);
    $next-req.add-cookies($cookies);

I think it's useful if HTTP::Response#next-request understands response's Set-Cookie header and automatically set Cookies to the next request.

[jonathanstowe]

Yep, that's almost certainly right, I'll see if I can do that this afternoon without breaking anything.

[jonathanstowe]

Hmm this would be fine, if the domain check was implemented properly on the add-cookies :(

I'm going to put another issue in to fix that first, before doing this, as I'd rather not be making things actually more insecure than they are.