Upgrade to DuckDB 0.10.2

[elefeint]

Changes to make it work:

1. Fivetran batch files contain VARCHAR values in columns of all types to denote "null" and "do not modify this" values.
   old_implicit_casting is required to load staged varchar data into typed columns; otherwise 0.10.2 runs into

Cannot mix values of type VARCHAR and
  INTEGER in CASE expression - an explicit cast is required

2. duckdb::DBConfig constructor changed, so I added properties one by one instead of preconstructing the map.

3. The test had a hardcoded database name, which for me is now, of course, readonly in 0.10 mode, so I refactored to make it easier to change the database name.