fix: Set-Cookie header issue

[M-Krilano]

This will allow multiple cookies to be set from the server by adding multiple 'Set-Cookie' fields within the header response.

Before this fix, if there was multiple 'Set-Cookie' fields, it would be merged into one string value and this is not allowed according to rfc6265 standard

Before Fix:

// Response Header
Set-Cookie: "cookie1=1 cookie2=2"

After Fix:

// Response Header
Set-Cookie: "cookie1=1"
Set-Cookie: "cookie2=2"