Issue # 3518920 by danrod: Added the new flatpickr.js changes in the 8.x-2.x branch

Closes #3518920

js/flatpickr.js

+/**
+ * @file
+ * 
+ * Callback for flatpickr.
+ */
+
+(function ($) {
+  Drupal.behaviors.flatpickr = {
+    attach:(context, settings) => {
+
+      const fieldName = [];
+
+      Object.keys(settings.timepicker.flatpickr_timepicker).forEach((key, index) => {
+        if (key !== null) {
+          fieldName[index] = key;
+        }
+      });
+      
+      const requiredOptions = {
+        enableTime: true,
+        noCalendar: true,
+        dateFormat: "H:i",
+       };
+
+      for (let i = 0; i < fieldName.length; i++) {
+        $('input[name="' + fieldName[i] + '[' + i + '][value][time]"').flatpickr(requiredOptions);
+      }
+    }
+  };
+
+}(jQuery));