Google URL shortener discontinued

[codingleo]

The google url shortening service will be discontinued, so I'll create a PR for firebase which will be the new url shortener from google.

News for url shortening discontinued: https://www.theverge.com/2018/3/31/17184164/google-alphabet-url-shortening-service-closed

Docs for new firebase url shortener (a.k.a. Dynamic Links): https://firebase.google.com/docs/dynamic-links/

[mremi]

Thanks @codingleo 👍