[Drupal 9.x] Update use of date_time_callbacks and date_date_callbacks in Webform

I would like to create a backward-compatible patch that would be supported via 8.x-5.x

The patch #2 looks good to me.
I made a code review. For me, documentation and logic look good.
I also tested it on three different Drupal environments:
Drupal 8.9.14
Drupal 9.2.1
Drupal 9.3.x

On all Drupal environments it works as expected and all three callback functions are properly called.
I'm re-adding the tests to see if tests pass on 9.3.x branch and than I move to RTBC.
I'm also attaching a webform config file with the webform that I tested the issue.

I don't know why the tests are passing locally but failing with test bots.

The tests might be broken because Drupal 9.3 is broken - see #3250335: #date_date_callbacks is broken in Drupal 9.3

+++ b/src/Plugin/WebformElement/DateList.php
@@ -57,7 +58,9 @@ class DateList extends DateBase {
+      $element['#date_date_callbacks'][] = (floatval(\Drupal::VERSION) >= 9.3)
+        ? '::dateListDateDateCallback'
+        : '_webform_datelist_date_date_callback';

+++ b/src/Plugin/WebformElement/DateTime.php
@@ -108,7 +108,9 @@ class DateTime extends DateBase {
-    $element['#date_date_callbacks'][] = '_webform_datetime_date';
+    $element['#date_date_callbacks'][] = (floatval(\Drupal::VERSION) >= 9.3)
+        ? '::dateTimeDateCallback'
+        : '_webform_datetime_date';

@@ -118,7 +120,9 @@ class DateTime extends DateBase {
-    $element['#date_time_callbacks'][] = '_webform_datetime_time';
+    $element['#date_time_callbacks'][] = (floatval(\Drupal::VERSION) >= 9.3)
+        ? '::dateTimeTimeCallback'
+        : '_webform_datetime_time';

Is this version check necessary necessary? I think previous versions of Drupal will work with the new array callback. See https://3v4l.org/Suleg

Also given changes on 6.x is not possible to make a patch that applies to both 6.x and 8.x-5.x

Given a single patch accross 6.x and 8.x-5.x is not possible because the callback have changed in 6.x recently going to change this to target 6.x

So the 6.x branch I just pushed should pass on 9.2.x and will fail on 9.3.x until #3250335: #date_date_callbacks is broken in Drupal 9.3 is fixed. Fingers crossed.

Oh well #9 is wrong because of the function_exists() check in Drupal 9.2 and lower... so the floatval trick is the way to go.

We also are affected by #3250349: \Drupal\Core\Datetime\Element\Datelist::processDatelist() does not use trusted callbacks - #date_date_callbacks only partially converted to TrustedCallbackInterface in 9.3.x

Now that webform tests are passing on 9.3.x I think this one ready too.

@alexpott Thank you for supporting backward compatibility.