http2: fix refs to status 205, add tests

Fix references within http2 core to HTTP_STATUS_CONTENT_RESET to point
to the correct HTTP_STATUS_RESET_CONTENT. Add tests for status 204,
205 & 304 in respond, respondWithFD & respondWithFile. Add general
error tests for respondWithFD & respondWithFile.

PR-URL: https://github.com/nodejs/node/pull/15153


Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Claudio Rodriguez <cjrodr@yahoo.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>