Fix handlers adding issue in the API form

[HashanTG]

#1235
Users can now add multiple handlers without requiring properties on each handler. Only the class name is required before adding another handler.
I tested it in my local machine. Check it :)

Resolves wso2/mi-vscode#1235

[CLAassistant]

All committers have signed the CLA.

[Copilot]

Pull Request Overview

This PR modifies the handler addition logic in the API form wizard to require only a class name before allowing users to add another handler, removing the previous requirement for properties.

• Simplified the validation check when adding new handlers by removing the properties requirement
• Users can now add handlers with just a class name, without needing to define properties first

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[ChinthakaJ98]

@HashanTG can you please update the commit messages? Refer https://cbea.ms/git-commit/ for some best practices.