Add tests for syncing single and multi props (#872)

Test failures:
- `test_model_sync_single_prop_05`: modifying the inner elements of a nested collection prop does not sync (eg. `tuple<array<int64>>`
- `test_model_sync_multi_prop_02`: assigning a new list to a multi-prop does not remove the previous values

Maybe not actual bugs
- `test_model_sync_single_prop_06` and `test_model_sync_multi_prop_08`: objects without a prop set will have it fetched if synced alongside objects with the prop set