Persist data within a session in 'new model/new dataset' form

[ots22]

At the moment, navigating away from the form before it's submitted, then back again, loses any partially completed form data.

Figure out how to get react-json-schema-form to persist this.

The source for the forms:

scivision/frontend/src/catalog_entry_form.js

Line 52 in d50f65f

<Form onSubmit={