EditForm: change API to allow form subission from code

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Is your feature request related to a problem? Please describe the problem.

Currentyle, it seems there's no way to submit an EditForm programatically from C# code because the HandleSubmitAsync method is private.

### Describe the solution you'd like

Adding a public method that submits the form would allows us to have forms without submit buttons (ex.: scenario where the user must pick items from lists and where picking an item should submit a form) and would allow us to reuse the context+validation logic currently implemented by the EditForm.

### Additional context

_No response_