Preferred batching implementation

[aniketfuryrocks]

Hi, @sfackler. First of all thanks for the amazing crate. We are working with high frequency data that we want to write to postgres in the most efficient manner possible. First thing that came into mind is to batch insert using prepared statements. But that's limited to a single number. Is there a more flexible implementation using which we can insert many rows in the most efficient way possible. Thanks https://github.com/blockworks-foundation/lite-rpc/pull/92

Current implementation that I think makes matter better, but know can be optimized further https://github.com/blockworks-foundation/lite-rpc/blob/f98c8f2e4cd01fad321a0c9ea86b004021c18e53/src/workers/postgres.rs

[sfackler]

A COPY query is generally the most efficient method to perform bulk inserts.