Firestore Bytes serializing not working on admin SDK[Firestore]

* Operating System version:w10
* Firebase SDK version: 13.1
* Firebase Product: Firestore
* Node.js version: 20.11
* NPM version: 10.3

When trying to store uint8array as Firestore.Bytes from admin-sdk throw a serializing error:

`Error: Value for argument "data" is not a valid Firestore document. Couldn't serialize object of type "Bytes" (found in field "binaryData"). Firestore doesn't support JavaScript objects with custom prototypes (i.e. objects that were created via the "new" operator).`

Uint8array seems to be the way to go, but then mismatch Web SDK (web sdk return bytes array as Firestore.Bytes objects).

#### Steps to reproduce:

```
import { Bytes } from "firebase/firestore";

const bin = new Uint8Array([0x48, 0x65, 0x6C, 0x6C, 0x6F]);

const fsBytes = Bytes.fromUint8Array(bin);

db.collection('your_collection').doc('your_document').set({
binaryData: fsBytes
});
```

从提供的 Node.js 复现开始，使用 Firebase SDK 13.1、Node.js 20.11 和 Admin SDK，重点关注 Firestore 文档序列化边界。未指定 repository 文件或测试；完成的标准是确定 Bytes/Uint8Array 表示是否可以一致地存储，并使用回归测试覆盖已确认的行为。

由索引模型根据 Issue 内容生成。