DB plugin queries

[coffee-cup]

• Add query support to firestore plugin. A query is a JSON object with type

export interface Query<T> {
  where?: [
    [keyof T, firebase.firestore.WhereFilterOp, any], // field, op, value
  ];
  orderBy?: [[keyof T] | [keyof T, "asc" | "desc"]];
  limit?: number;
}

• Add support to watch single document
• Change watchAll to take in an optional query
• Change how queries and docs are stored in the universe db cache. db_cache.docs should always be kept up to date with what is being watched

This plugin is not finalized yet as it isn't testable. The next step is to allow passing in fixtures that can mock firestore.

Type of Collection is

export interface Collection<T extends { id: string }> {
  ref: (key: string) => firebase.firestore.CollectionReference;

  // methods for actions
  get: (id: string) => Promise<T>;
  getAll: () => Promise<T[]>;
  set: (id: string, value: Partial<T>) => Promise<void>;
  delete: (id: string) => Promise<void>;
  insert: (value: Omit<T, "id">) => Promise<string>;
  query: (query: Query<T>) => Promise<T[]>;

  // methods for react components
  watch: (id: string) => Fetching<T>;
  watchAll: (query?: Query<T>) => FetchAll<T>;
}