feat: add navigation sort configuration to MailResource

Author: somegooser

config/filament-mails.php

@@ -13,5 +13,6 @@
 
     'navigation' => [
         'group' => null,
+        'sort' => null,
     ],
 ];

src/Resources/MailResource.php

@@ -61,6 +61,11 @@ public static function getNavigationGroup(): ?string
         return config('filament-mails.navigation.group', __('Emails'));
     }
 
+    public static function getNavigationSort(): ?int
+    {
+        return config('filament-mails.navigation.sort');
+    }
+
     public static function getNavigationLabel(): string
     {
         return __('Emails');