[3.13] gh-79986: Add parsing for References/In-Reply-To email headers (GH-137201...

[3.13] gh-79986: Add parsing for References/In-Reply-To email headers (GH-137201) (#142574)

gh-79986: Add parsing for References/In-Reply-To email headers (GH-137201)

This is a followup to 46d88a113142b26c01c95c93846a89318ba87ffc (GH-13397),
which added parsing for Message-ID. Similar handling is needed for the
other two identification headers.
(cherry picked from commit 79aa43a9797de64a3c42794f34329eab638dd67a)

Co-authored-by: elenril <anton@khirnov.net>