Provide a way to enable navigation to all form pages when using multi page forms

[mishterk]

When a multi page form loads, subsequent form pages are greyed out and cannot be navigated directly to until the 'next' button has been used to access the page. Once the page has been accessed using the 'next' button, the page can easily be jumped to via the form navigation.

We need to add some means of enabling form stages in the UI, perhaps at the field level.

Current workaround is to modify form properties as demonstrated in this support reference and suggested in this related ticket.