fix: fix migration losing data and other small bugs

The main issue was that a migration in 3.0.0 was discarding some fields of the submission data. (3.0.1 had the same problem.) I've fixed this, and also keep clones of affected tables in case further issues are discovered in future.

Two further fixes were added for bugs encountered in testing:

• Some task email notification logs had a null emailTemplateId in the DB (not sure why): this was crashing the decision page. I've made this more lenient.
• If an invited reviewer declined and gave a reason for declining, the decision page would crash. A bug introduced with translations. Fixed.