Push Notifications instrumentation

### Description

We could use bytecode manipulation to instrument third party push notification solutions (probably start with FCM as the most popular one), to capture breadcrumbs automatically with all the metadata like title,body,message id,sender, etc. (see [Firebase remote message](https://firebase.google.com/docs/reference/android/com/google/firebase/messaging/RemoteMessage) for reference).

This can certainly help in solving or prioritizing crashes or ANRs.

We could even go as far as sending this as app context and make it searchable, e.g. to filter crashes/ANRs that happened during application creation from a push notification (=cold start).

該 issue 將 FCM 和 Firebase RemoteMessage 列為起始參考。釐清 instrumentation 範圍和 metadata contract，然後驗證 push 事件會產生可用於搜尋 cold-start crashes 和 ANRs 的 breadcrumbs 與 app context。

由索引模型根據 Issue 內容生成。