Add prefill option for demos

[n-d-r-d-g]

Add an option to prefill forms with dummy data. This can be useful for demos.

One way of achieving this is via shortcut keys. Another one is a hidden button.

Note: The chosen option has to be hidden to the public.

[n-d-r-d-g]

The shortcut keys options will only work for devices using a keyboard. I think a better solution is to have two buttons:

• Load dummy data
• Clear form

The clear button will be useful right after a user has loaded dummy data and saw the preview. This acts as a quick way to provide value to the user without going through the hassle of filling the whole form.