Impossible to translate "ago" on the list of private messages

PR in progress here: https://github.com/goalgorilla/open_social/pull/3663

Note that the patch failed testing (and the way it's currently written won't actually allow it to be picked up by the translation tools for localize.drupal.org so https://www.drupal.org/project/drupal/issues/3410052 🐛 Impossible to translate "ago" for "timestamp_ago" formatter Active also still needs work).

The status of how to do it via UI is still unclear, and the github issue has been closed, saying that there are details in a JIRA ticket. Here is how I accomplished the translation for french using the config files:

Create a new file called core.entity_view_display.private_message.private_message.inbox.yml in your default config/language/<langcode_here> directory. In my case, the contents of this file are:

langcode: fr
content:
  created:
    settings:
      past_format: 'il y a @interval'

Make sure to update the langcode value if you are translating a different language.

Create a new file called core.entity_view_display.private_message.private_message.default.yml in the same directory. Similarly, my contents were:

content:
  created:
    settings:
      past_format: 'il y a @interval'

Import config, and the private messages interface should be translated properly. I did not translate the future_format because I never expect to receive a private message from the future. You can translate that by adding the future_format key just above the past_format key.