User cannot create account using sign with apple with email-less account

### Description

Users cannot create an account with firebase because when they signing with apple, they are not using email, they use a phone number.

https://support.apple.com/en-gb/HT207944

### Reproducing the issue

Signing with apple using a phone number is allowed in some countries. Review sign with apple doc.

### Firebase SDK Version

-

### Xcode Version

-

### Installation Method

Swift Package Manager

### Firebase Product(s)

Authentication

### Targeted Platforms

iOS

### Relevant Log Output

_No response_

### If using Swift Package Manager, the project's Package.resolved

_No response_

### If using CocoaPods, the project's Podfile.lock

_No response_