Add support for a prompt with a message AND an ok button

[ccruzagralopes]

The current message prompt in TH doesn't have any buttons. That's expected for simulated test cases, so it needs to exist. But now we have a new scenario where we need a message prompt that needs the user to confirm they did some action, so we need an OK button in the prompt.

Suggestion: add an ok_button boolean parameter to the message_request prompt type.