Features

Would love to see the new features from Firestore integrated into AngularFire. Mainly "Aggregation Queries".

### Version info

**Angular:**

**Firebase:**

**AngularFire:**

**Other (e.g. Ionic/Cordova, Node, browser, operating system):**

### How to reproduce these conditions

**Failing test unit, Stackblitz demonstrating the problem**

**Steps to set up and reproduce**

**Sample data and security rules**

### Debug output

** Errors in the JavaScript console **

** Output from `firebase.database().enableLogging(true);` **

** Screenshots **

### Expected behavior

### Actual behavior

尚未識別任何檔案、測試或進入點。請先檢視 AngularFire 的 Firestore 整合與 Firebase 的 Aggregation Queries 文件；若要視為完成，必須為所要求的功能定義 AngularFire API，並涵蓋其行為。

由索引模型根據 Issue 內容生成。