Enhancement: Support custom response for batch actions

[jowilf]

Enhance the @action decorator to support custom responses, such as redirects or rendering HTML pages, instead of just returning strings (related to #205)

Todo:

• Add a custom_response flag to the @action decorator function (default: False).
• Update submitAction() in list.js to handle custom responses.
• Modify handle_action in the base admin class to support custom responses.
• Ensure backward compatibility.
• Include an example in custom_actions example
• Add tests.
• Update the documentation