Updates the provided extension if a new version is available.
extension - the extension to be updated.
onSuccess - (optional) callback invoked if the extension was updated successfully,
providing access to the WebExtension object for bi-directional messaging, if null is provided
that means that the WebExtension hasn’t been change since the last update.
onError - (optional) callback invoked if there was an error updating the extension.
This callback is invoked with an UnsupportedOperationException in case the engine doesn’t
have web extension support.