[REF] owl: move metadata into __info__

This differentiate better metadata and owl exported values.  Also, and
this is the goal, it gives a space to add extra keys in the future.

src/index.ts

@@ -17,5 +17,7 @@ export { QWeb } from "./qweb_core";
 export { connect, Store } from "./store";
 import * as _utils from "./utils";
 
+export const __info__ = {}
+
 
 export const utils = _utils;