Revert "Issue #2953227 by vtcore: Date Time enhancer does not work with Date range fields"

This reverts commit 5d80d634.

src/Plugin/jsonapi/FieldEnhancer/DateTimeFromStringEnhancer.php

@@ -19,20 +19,6 @@ class DateTimeFromStringEnhancer extends DateTimeEnhancerBase {
    * {@inheritdoc}
    */
   public function postProcess($value) {
-    if (is_array($value)) {
-        return array_map([$this, 'processSingleValue'], $value);
-    }
-
-    return $this->processSingleValue($value);
-  }
-
-  /**
-   * Process a single value
-   *
-   * @param $value
-   * @return string
-   */
-  protected function processSingleValue($value) {
     $storage_timezone = new \DateTimezone(DATETIME_STORAGE_TIMEZONE);
     $date = new \DateTime($value, $storage_timezone);
 
@@ -48,20 +34,6 @@ class DateTimeFromStringEnhancer extends DateTimeEnhancerBase {
    * {@inheritdoc}
    */
   public function prepareForInput($value) {
-    if (is_array($value)) {
-        return array_map([$this, 'prepareSingleValue'], $value);
-    }
-
-    return $this->prepareSingleValue($value);
-  }
-
-  /**
-   * Prepare a single value for input.
-   *
-   * @param $value
-   * @return string
-   */
-  protected function prepareSingleValue($value) {
     $date = new \DateTime($value);
 
     // Adjust the date for storage.