Summary:
- Small cleanup: Make DocStorage implement OnDemandStorage, and remove unused execWithBackup
- Upgrade to new versions (.3) of @gristlabs/sqlite3 and connect-sqlite3 to use dbstat
- Add _logDataSize method which queries dbstat, adding up pgsize for tables loaded into the data engine
- Only complete _logDataSize every 5 minutes using new field _lastLoggedDataSize
Test Plan: Tested manually
Reviewers: paulfitz
Reviewed By: paulfitz
Differential Revision: https://phab.getgrist.com/D3277