Implement needsMultifactorCode with userId and nonceinfo delegate in StoredCredentialsAuthenticator

[staskus]

Fix login being stuck in a loading state when the account has 2FA with passkeys enabled.

Fix implements needsMultifactorCode(forUserID userID: Int, andNonceInfo nonceInfo: SocialLogin2FANonceInfo) delegate which is called when nonceInfo != nil which presents 2FA login.

Context: p1706533264603049-slack-C012H19SZQ8

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https://github.com/wordpress-mobile/WordPressAuthenticator-iOS/assets/4062343/9874afb2-188d-424d-b656-da03b9f6b9d2

• [ ] I have considered if this change warrants release notes and have added them to the appropriate section in the CHANGELOG.md if necessary.

[staskus]

@Ecarrion 👋 Letting you know. We've noticed on the JP app that login from the home screen doesn't work if the account has 2FA with passkey enabled.

[staskus]

Thank you for reviews, @guarani @Ecarrion!