Bind external properties to a dedicated class.

[maciejwalkowiak]

📜 Description

Bind external properties to a dedicated ExternalOptions class.

💡 Motivation and Context

This allows to turn nullable Boolean fields from SentryOptions into a non-nullable boolean and keep simple getter and setter, without breaking Java beans standard.

Fixes #1738.

💚 How did you test it?

📝 Checklist

• I reviewed the submitted code
• I added tests to verify the changes
• I updated the docs if needed
• No breaking changes

🔮 Next steps