Add a new frontpage user message fonctionality

[jma]

How it works

A message system already exists for the login page. It would be great to have a similar functionality on the frontpage.

Improvement suggestion

Using a cli, it would be possible to add a user message on the frontpage to announce a new release or other kind of message.

Nice to have

A generic system with a publication start and end date, a enable flag and a regex on the URL to display the message.

[github-actions]

This issue is stale because it has been open 6 months with no activity.