Add SQL tracing

[adamvr]

Hey Blobs!

This is mostly just conversation starter / prototype to try out sql tracing using XSAM/otelsql. It currently only adds sql traces to the sql_raw processor since it (and the sql_raw output) don't mash their messages together so there is still a 1-1 parent-child relationship between incoming and outgoing messages. Maybe this PR is actually about span linking (https://opentelemetry.io/docs/concepts/signals/traces/#span-links) in cases where we do turn batches into single sql queries.