FR: User.fromJSON

### Operating System

macOS

### Browser Version

Safari 16.5.2

### Firebase SDK Version

10.1.0

### Firebase SDK Product:

Auth

### Describe your project's tooling

index.html with source tag.

### Describe the problem

I would like the [users](https://firebase.google.com/docs/reference/js/auth.user) to a have a [fromJSON](https://firebase.google.com/docs/reference/js/auth.emailauthcredential.md#emailauthcredentialfromjson) static method, similar to all the classes that inherit [AuthCredential](https://firebase.google.com/docs/reference/js/auth.emailauthcredential).

Currently, there is no way to `JSON.stringify` a user and turn it back to a normal user.

### Steps and code to reproduce issue

There are no steps.