Support MERGE operation

[Rid]

Postgres 15 introduced the merge operation: https://supabase.com/blog/new-in-postgres-15

It would be great if supabase-js can support this operation to simplify upserts.

[steve-chavez]

You can do the equivalent of MERGE with upsert(), internally it uses ON CONFLICT - which should give you similar capabilities.

See: https://pganalyze.com/blog/5mins-postgres-15-merge-vs-insert-on-conflict