Fill out testing

[danvk]

• [ ] Split select unit/type tests
• [x] Add unit tests to check that all queries are idempotent
• [x] Run pg-to-ts on the test schema via GitHub actions
• [x] Update without a where clause
• [x] Update with fixed columns and a Set parameter
• [x] Update with fixed columns and limitOne
• [x] Dynamic update with a Set parameter