Form does not emit a message upon cancel

### Current Behavior

I created a dialo with a form but I could not close the form with the cancel button since the cancel button does not emit an event.

### Expected Behavior

Cancel button should emit an event

### Steps To Reproduce

Create a dialog
Add a form
Open the dialog using UI control
Operate the cancel button.

### Environment

- Dashboard version: 1.25
- Node-RED version:
- Node.js version:
- npm version:
- Platform/OS:
- Browser:

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate