API: Add show_sitetree_link_tracking config to SiteTreeLinkTracking extension to control visibility of the Link Tracking tab

_config/linktracking.yml

@@ -4,3 +4,8 @@ Name: cmslinktracking
 SilverStripe\ORM\DataObject:
   extensions:
     - SilverStripe\CMS\Model\SiteTreeLinkTracking
+---
+Name: cmslinktrackingvisibility
+---
+SilverStripe\Security\Member:
+  show_sitetree_link_tracking: true

code/Model/SiteTreeLinkTracking.php

@@ -4,6 +4,8 @@ namespace SilverStripe\CMS\Model;
 
 use DOMElement;
 use SilverStripe\Assets\Shortcodes\FileLinkTracking;
+use SilverStripe\Forms\FieldList;
+use SilverStripe\Forms\FormScaffolder;
 use SilverStripe\ORM\DataExtension;
 use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\FieldType\DBHTMLText;
@@ -52,6 +54,15 @@ class SiteTreeLinkTracking extends DataExtension
         ],
     ];
 
+    /**
+     * Controls visibility of the Link Tracking tab
+     *
+     * @config
+     * @see linktracking.yml
+     * @var boolean
+     */
+    private static $show_sitetree_link_tracking = false;
+
     /**
      * Parser for link tracking
      *
@@ -194,4 +205,13 @@ class SiteTreeLinkTracking extends DataExtension
             $domReference->removeAttribute('class');
         }
     }
+
+    public function updateCMSFields(FieldList $fields)
+    {
+        if (!$this->owner->config()->get('show_sitetree_link_tracking')) {
+            $fields->removeByName('LinkTracking');
+        } elseif ($this->owner->ID && !$this->owner->getField('LinkTracking')) {
+            FormScaffolder::addManyManyRelationshipFields($fields, 'LinkTracking', null, true, $this->owner);
+        }
+    }
 }