Warn about changes in the initial submission form

The context is as follows:

• The author has submitted the initial form
• The editor has assigned a datatype
• The author goes back into the form to fill out the second part of it

At this moment, the author could still make changes to the initial part of the form.
We should keep track of the touched fields, and show the editors a warning about them.

A first version could simply mark the fields with colorWarning.
A future version could also potentially show the field's previous state.