sql, kv: support non-enum user-defined types with COL_BATCH_RESPONSE scan format #92954
Description
When implementing the projection pushdown into the KV (#82323), at least initially, we won't support user-defined types other than enums. The difficulty is that these types require hydration, but it seems non-trivial to inject that on the KV server side.
Jira issue: CRDB-22065