Create DrupalDateTime.stub (#794)

* Create DrupalDateTime.stub

* Create DateTimePlus.stub

* Update DrupalDateTime.stub

Author: mglaman

stubs/Drupal/Component/Datetime/DateTimePlus.stub

@@ -0,0 +1,7 @@
+<?php
+
+namespace Drupal\Component\Datetime;
+
+class DateTimePlus {
+
+}

stubs/Drupal/Core/Datetime/DrupalDateTime.stub

@@ -0,0 +1,9 @@
+<?php
+
+namespace Drupal\Core\Datetime;
+
+use Drupal\Component\Datetime\DateTimePlus;
+
+class DrupalDateTime extends DateTimePlus {
+
+}