fix: make loadUserInfo configurable instead of hardcoded

[hannal]

Summary

• Allow users to configure loadUserInfo option instead of hardcoding it to true
• Maintain backward compatibility by defaulting to true when not specified

Problem

The loadUserInfo option was hardcoded to true, preventing users from disabling the userinfo endpoint call even when they have "User Info inside ID Token" enabled in their ZITADEL application settings.

Fixes #46

Changes

• Modified createZitadelAuth() to use zitadelConfig.loadUserInfo ?? true instead of hardcoded true

[elinashoko]

Thanks for your contribution, we'll have a look as soon as we can.