Improve listing of notification messages [#3592569]

Problem/Motivation

The default listing shows the oldest notification message first. In keeping with other listings in Drupal, sort by publish date newest first, and make the headers click-sortable.

Remaining tasks

Provide a patch

User interface changes

Clickable columns in /admin/content/notification-message: Publish Date, Unpublish Date, Status
Sorted by default by latest publication date

Issue fork notification_message-3592569

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3592569-improve-listing-of changes, plain diff MR !27
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