Option to append "See merge request ---" to squashed commit messages

Ultimate customer here:

Proposal

As a basic example, look at the most recent commit to gitlab d0d366ca . At the end of the commit it says

See merge request !52429 (merged)

However, if you use the Squash and Merge feature in GitLab, while you can edit the squashed message, it is a tad annoying to put "See merge request" at the end of the squashed message. And more importantly, if someone FORGETS to edit their squashed commit message before merging, then the reference to the MR will not be included.

This proposal suggests an option to automatically append "See merge request ---" to the end of squashed commit messages.

Related to #26748

Related to gitlab-foss#53269 (closed)

Related to gitlab-foss#49013 (moved)

Related to #21686 (closed)

Related to gitlab-foss#49010 (moved)