Add configuration option to hide official templates

Introduce a new environment variable and configuration option to allow users to hide official templates in the template gallery. This provides more flexibility for self-hosted instances of OpnForm.

api/app/Http/Controllers/Forms/TemplateController.php

@@ -14,7 +14,7 @@ class TemplateController extends Controller
 {
     private function getProdTemplates($slug = false)
     {
-        if (!config('app.self_hosted')) {
+        if (!config('app.self_hosted') || !config('opnform.show_official_templates')) {
             return [];
         }
 

api/config/opnform.php

@@ -5,4 +5,5 @@ return [
     'moderator_emails' => explode(',', env('MODERATOR_EMAILS') ?? ''),
     'template_editor_emails' => explode(',', env('TEMPLATE_EDITOR_EMAILS') ?? ''),
     'extra_pro_users_emails' => explode(',', env('EXTRA_PRO_USERS_EMAILS') ?? ''),
+    'show_official_templates' => env('SHOW_OFFICIAL_TEMPLATES', true),
 ];