pg_clickhouse v0.10: Subquery pushdown and 1000x faster TPC-H queries

Continuing our investment in pg_clickhouse, improving pushdown coverage for analytic workloads has remained our top focus, with full pushdown across the TPC-H benchmark suite as our immediate metric. We've had a lot of progress since our last update in June , including on the TPC-H scoreboard, which we haven't really talked about since our introductory post back in December, so that's where we'll start. With the release of v0.10.0, our scoreboard has moved from 12 of 22 TPC-H queries fully pushed down to 16, leaving only 6 to go to finish off the set.