doc: add http highlight grammar

Prior to this commit, http request message code blocks in Markdown
files were not being highlighted correctly. This has been corrected by
adding the new grammar to the bundle, removing the CRLFs (`\r\n`) from
these code samples, adding a reminder to re-add them, and tuning the
syntax theme to support attribute highlighting.

PR-URL: https://github.com/nodejs/node/pull/33785


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>