support hard_deletes `new_record` behavior for snapshots

As of dbt-core 1.9 snapshot hard_deletes config supports `new_record` which this adaptor does not support.
https://docs.getdbt.com/reference/resource-configs/hard-deletes

`invalidate` behavior works just fine, but when running snapshots with `new_record`, the `dbt_is_deleted` column is never populated.