bug#36208: 26.2.50; Add tooling for commit message format checking

[Noam Postavsky]

Damien Cassou <damien@cassou.me> writes:

> 1. dots after every sentence (even just "New function" must terminate
>    with a dot)
> 2. double-space after dots ending sentences

>   - for check 6., a shortcut (beyond `C' which triggers
>     `magit-commit-add-log-insert') could add a template with all the
>     changes

I've started work on a command which can generate the ChangeLog
skeleton, see https://debbugs.gnu.org/16301#11.  While doing that, I
found that we already have log-edit-mode (and derived mode
vc-git-log-edit-mode) which already has some checking for 1 and 2 in its
font-lock rules.