unpack prepacked plugins on plugins initialization (#9149)

* unpack prepackaged plugins on plugins initialization

* leverage utils.FindDir

i18n/en.json

@@ -3074,6 +3074,10 @@
     "id": "app.plugin.install_id.app_error",
     "translation": "Unable to install plugin. A plugin with the same ID is already installed."
   },
+  {
+    "id": "app.plugin.install_id_failed_remove.app_error",
+    "translation": "Unable to install plugin. A plugin with the same ID is already installed and failed to be removed."
+  },
   {
     "id": "app.plugin.invalid_id.app_error",
     "translation": "Plugin Id must be at least {{.Min}} characters, at most {{.Max}} characters and match {{.Regex}}."