+ * @param array|string $options Language code or options array
+ * - string 'lang' Language code
+ * - string 'dir' Language direction (ltr or rtl)
+ * - string 'modules' Pipe-separated list of module names
+ * - string|null 'only' "scripts" (unwrapped script), "styles" (stylesheet), or null
+ * (mw.loader.implement).