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

Rebasing the MR, will try to resolve the test failures.

Fixed tests and phpcs. phpstan fails are in HEAD.

@acbramley great, thanks! Just some last phpstan things left... :)

EDIT: SORRY, didn't see they are unrelated here indeed!

@acbramley I left a comment. Anyway it would be great to get some feedback from the folks here to get it RTBC'd!

Version constraint changes can be done in another issue.

@acbramley I'm fine with that, if that issue also removes the comment added here.

The possible values are "before", "after" or "invisible" so it needs constraint and update hook to populate default value (BC)

Some warning should be visible in logs if update is not executed so UI should also warn about unconfigured option

PS: Left few comments in MR

I'm not sure we need an upgrade hook here since it's optional config?