src: rename http2 class and suppress compile warnings

Suppress compile warnings on Windows, rename class for
consistent styling.

Signed-off-by: James M Snell <jasnell@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/32551


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>