Adding Async Streaming to Postgres Foreign Data Wrappers

Supabase Wrappers introduces asynchronous streaming between databases for Postgres Foreign Data Wrappers. Traditional FDWs like postgres_fdw and mysql_fdw use synchronous, pull-based models that block Postgres during I/O. The new Rust-based approach enables non-blocking streaming, reducing memory pressure and improving interactivity for analytical workloads against systems like ClickHouse.