Add support for #description_display for container types that support it

Just tried to apply this. There seems to be an incompatibility with some other patches.
Maybe it would help to make a new dev version.

  - Installing drupal/field_group (dev-3.x 710c6a6): Cloning 710c6a6436 from cache
  - Applying patches for drupal/field_group
    https://www.drupal.org/files/issues/2020-04-23/3130339-2.patch (Horizontal vertical tabs set default tab to last item with #open = TRUE #2)
    https://www.drupal.org/files/issues/2023-04-07/2787179-highlight-html5-validation-85.patch (Ensure visibility of invalid fields JS = TRUE #85)
    https://www.drupal.org/files/issues/2022-08-10/3302908-2.patch ($this->t should be used instead of t = TRUE #2)
    https://www.drupal.org/files/issues/2023-01-12/3098550-17.patch (Nested groups render on other entity forms (or when fields are inaccessible) when they shouldnt #17)
    https://www.drupal.org/files/issues/2022-10-27/3205504-20.patch (Add support for #description_display for container types that support it)
   Could not apply patch! Skipping. The error was: Cannot apply patch https://www.drupal.org/files/issues/2022-10-27/3205504-20.patch
    https://www.drupal.org/files/issues/add_classes_js-2936973-2.patch (Add classes to JS rewriting in horizontal tabs)

Would be great, if this could be turned into a MR please for final review and testing.

I turned the patch into an MR.

Thanks @DamienMcKenna - now tests are failing and PHPStan is unhappy. Back to NW for the final steps.

Patch in #20 applies correctly but the MR mentioned in #29 is not applying. Not sure if I created the patch from the MR wrong. I just added .patch to the MR link like this: https://git.drupalcode.org/project/field_group/-/merge_requests/56.patch