Add callback functions into crud

[robcxyz]

Would be really nice to have the ability to configure a callback for a given crud object. In this way we can then configure de-duplication of primary keys as a configurable property of the crud object.

• Right now we are only doing upserts but this will later be configurable within the crud struct
• Right now we only have one topic that needs ack so it is simple but future of crud package will have numerous

Order of operations

• Should be able to run the callback before / after the Tx
  • TODO: Look into patterns with channels to receive callback from db tx
    • Almost certainly we need to mod the channel input but worth investigating patterns

Uses

• dedupe
• ack callback
  • Would need to also include the offset / partition / topic in the message
  • Ack needs to happen after a successful transaction with DB
    • Would require creating a new channel to be able to handle this struct -> needs to have the offset data
    • or
    • Look into reading msg before ack into some kind of buffer
• Enrichment post dedup
  • TODO: List additional use cases / patterns where this is needed -> can think of several but should be formalized