[Epic] Add Support for `ENVELOPE UPSERT` in Platform

[nmeagan11]

Initiative and Theme

Materialize is Friendly; Materialize works with your existing pipelines

Problem

Subset of https://github.com/MaterializeInc/materialize/issues/13044 and related to https://github.com/MaterializeInc/materialize/issues/13121#issuecomment-1165140138. This is our second highest priority envelope to support in Platform, behind ENVELOPE DEBEZIUM.

Success Criteria

Users can successfully execute a CREATE SOURCE ... FROM KAFKA ... ENVELOPE UPSERT statement.

QA Sign-off

• [ ] Make sure ENVELOPE UPSERT is present in all relevant tests and testing frameworks.

Time Horizon

Medium

Blockers

None

[umanwizard]

The code for this has now landed, with the caveat that errors are un-retractable until https://github.com/MaterializeInc/materialize/issues/14084 lands.

Leaving the issue open pending QA signoff as the code is still only very lightly tested

[philip-stoev]

ENVELOPE UPSERT is now present in both Zippy and Platform Checks, so this is good to go.