Keep current partial submission instead of creating a new partial submission on session time-out

[lhalaa]

During the first partial save or when the session expires, it creates a new partial submission.

1. Every time the user hit "next" or "prev" after the session timed out, it will create a new submission
   This can be handled in a way that when the session has expired, the user will be redirected to the "intro" screen.

2. When a new submission is created, it saves without a parent
   Without a parent creates an "AccordionItems" as parent (first DataObject found) and will later be updated with the correct parent data. To fix this, we can add a hidden field to the form which contains the UserDefinedForm ID, and pass this data when saving partial submission.