Better support for widgets overriding their URLs

Move the URL processing into AppTile so that the widget can have a
URL used for embedding in the page and a separate one for popping
out into a browser.

src/components/views/elements/PersistentApp.js

@@ -1,6 +1,6 @@
 /*
 Copyright 2018 New Vector Ltd
-Copyright 2019 The Matrix.org Foundation C.I.C.
+Copyright 2019, 2020 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -75,11 +75,7 @@ export default createReactClass({
                 const AppTile = sdk.getComponent('elements.AppTile');
                 return <AppTile
                     key={app.id}
-                    id={app.id}
-                    eventId={app.eventId}
-                    url={app.url}
-                    name={app.name}
-                    type={app.type}
+                    app={app}
                     fullWidth={true}
                     room={persistentWidgetInRoom}
                     userId={MatrixClientPeg.get().credentials.userId}