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
});
```

Start with the supplied Node.js reproduction using Firebase SDK 13.1, Node.js 20.11, and the Admin SDK, focusing on the Firestore document serialization boundary. No repository file or test is named; done means establishing whether the Bytes/Uint8Array representations can be stored consistently and covering the confirmed behavior with a regression test.

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