HTTP: introduced raw headers API.
HTTP: introduced raw headers API.

1) r.rawHeadersIn returns an array of key-value pairs exactly as they
were received from the client.

2) r.rawHeadersOut returns an array of key-value pairs of respose
headers.

Header names are not lowercased, and duplicates are not merged.

nginx/njs,nginx/njs,nginx/njs,nginx/njs,nginx/njs,nginx/njs