Merge sendmail 8.18.1 from stable/13 to releng/13.3

Merge sendmail 8.18.1 from stable/13 to releng/13.3

Merge commit '850ef5ae11d69ea3381bd310f564f025fc8caea3'

Merge vendor sendmail 8.18.1 into HEAD

(cherry picked from commit d39bd2c1388b520fcba9abed1932acacead60fba)

Add new source file for sendmail 8.18.1

(cherry picked from commit 19d4fb85bf17579780e8f0c3cbae8a5e92a6922e)

New sendmail 8.18.1 cf file

(cherry picked from commit 1b6a5580c1f999fb1ba5f9860cf63a8aefc55b3c)

Minor change to update these files so new freebsd*.cf files are
generated

(cherry picked from commit 2c191ba6b0b5d1b3729a5ac428d51cfc5d5f3d2e)

Belatedly update version and date for sendmail 8.18.1 upgrade

(cherry picked from commit 31fbc98c949bfca30ab55afef04b4396a61b7e92)

Add a note about sendmail 8.18.1's stricter SMTP protocol enforcement
(akin to commit 21c1f1deb6a3ac6a60e4516261e5264a28e0b7a6 in main)

Update import date for stable/14

Relnotes:	Yes
Security:	CVE-2023-51765
Approved-by:	re (cperciva)
(cherry picked from commit a64caf2cb2dc3ddd6f325e323c281d1463a80ccf)