Created a batch action extension for LeftAndMain

+ Created an extension to add the `BatchActionParameters` fields from CMSMain to the `BatchActionsForm` in LeftAndMain
+ Applied the extension to LeftAndMain using YAML

_config/config.yml

@@ -4,6 +4,7 @@ Name: cmsextensions
 SilverStripe\Admin\LeftAndMain:
   extensions:
     - SilverStripe\CMS\Controllers\LeftAndMainPageIconsExtension
+    - SilverStripe\CMS\Controllers\LeftAndMainBatchActionsExtension
 ---
 Name: cmsmodals
 ---

code/Controllers/LeftAndMainBatchActionsExtension.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace SilverStripe\CMS\Controllers;
+
+use SilverStripe\CMS\Controllers\CMSMain;
+use SilverStripe\Core\Extension;
+
+class LeftAndMainBatchActionsExtension extends Extension
+{
+    public function updateBatchActionsForm(&$form)
+    {
+        $cmsMain = singleton(CMSMain::class);
+        $form->Fields()->insertAfter('Action', $cmsMain->BatchActionParameters());
+        return $form;
+    }
+}