Summary:
- Implement UI with "Apply to new records" and "Apply on record changes"
checkboxes, and options for selecting which changes to recalculate on.
- For consistency, always represent empty RefList as None
- Fix up generated SchemaTypes to remember that values are encoded.
Included test cases for the main planned use cases:
- Auto-filled UUID column
- Data cleaning
- NOW() formula for record's last-updated timestamp.
- Updates that depend on other columns.
Test Plan: Added a browser test.
Reviewers: jarek
Reviewed By: jarek
Subscribers: paulfitz
Differential Revision: https://phab.getgrist.com/D2885
