Core extensions to support database replication

[jorritsandbrink]

Feature description

Extend the core to enable database replication. This needs to be done before #933.

Context:

1. https://dlthub-community.slack.com/archives/C06EYJ2Q37C/p1707135498114549?thread_ts=1706550675.731069&cid=C06EYJ2Q37C
   

2. Postgres database replication #933 (comment)
   

Are you a dlt user?

None

Use case

Database replication, CDC, efficient incremental processing

Proposed solution

No response

Related issues

#933

[jorritsandbrink]

@rudolfix It seems like typically the entire record is provided for update operations, even if only a subset of columns has been changed. I checked Postgres, MySQL, SQL Server, and Delta tables.

Do we need partial updates?

[rudolfix]

@jorritsandbrink does it make things easier? I assume in that case we could reuse existing merge job right? then we do need only a flag to delete records because existing code handles replace rows and inserts by checking the primary keys.

it would be cool to have partial updates but if that is 2x more work then let's do the above instead