extensible timestamp rendering for DuckDB

[jraymakers]

When using the DuckDB dialect, if a timestamp value is an object with a toDuckDBString method, render the timestamp using that method instead of using JS Date to render it as an ISO string. This enables a wider range of rendering options for DuckDB timestamps, including matching the native DuckDB timestamp format.

[jraymakers]

There's a couple failing checks that I don't understand, but don't seem related to my change. Should I merge anyway?

[antonycourtney]

There's a couple failing checks that I don't understand, but don't seem related to my change. Should I merge anyway?

Those look like intermittent CI issues, go ahead and merge! Thanks.