Version 8.4.0
### 8.4.0:
- Changes
- General: Added support for Android x86 64.
- Firestore: Improved the efficiency of progress callbacks in
`LoadBundleAsync()`.
- Firestore: Fixed crashes in Unity Editor on Linux caused by C++ exceptions
failing to be converted to C# exceptions.
- Firestore: Fixed intermittent hangs on Android when exceptions are thrown
by callbacks.
- Firestore: Fixed a crash on Android when `DocumentReference.Set()` was
invoked with an invalid `documentData` value (e.g. an int).
- Firestore: Fixed race conditions in the instance caching, terminate, and
disposal logic of `FirebaseFirestore`.