Help! Add Support for FireStore

[OR13]

https://firebase.google.com/docs/firestore/

Are you excited for firestore?

want to learn how to use it by extending our persistence class to support a configurable collections based cache for each of the readModelTypes?

  export interface IPersistenceStore {
    getItem: (key: string) => Promise<Object>
    setItem: (key: string, value: Object) => Promise<Object>
  }

the key string here will always contain the type.

Instead of using local storage, we should be using an indexed collection with Firestore!