http: enable call chaining with setHeader()

Make `response.setHeader` return the response object itself
so that multiple header setting can be chained.

Fixes: https://github.com/nodejs/node/issues/33148

PR-URL: https://github.com/nodejs/node/pull/35924


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ricky Zhou <0x19951125@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>