Add empty locale extender to clear cache properly on enable/disable.

See https://github.com/flarum/core/pull/2020#issuecomment-616149583

extensions/emoji/extend.php

@@ -26,5 +26,7 @@ return [
             $config->Emoticons->add(':\'(', '😢');
             $config->Emoticons->add(':O', '😮');
             $config->Emoticons->add('>:(', '😡');
-        })
+        }),
+
+    new Extend\Locales(__DIR__.'/locale'),
 ];