Problem/Motivation
The code from SqlContentEntityStorageSchemaConverter was somewhat generic but mostly targeted for converting an entity type from non-revisionable to revisionable, and it had a big flaw: it was relying on live (in-code) entity type and field storage definitions for the conversion process.
We managed to change that code to be completely agnostic of the conversion type and not use the live definitions anymore in #2984782: Add an API for converting entity type schemas to (non-)revisionable/(non-)translatable, with or without data, so SqlContentEntityStorageSchemaConverter does not have any purpose to exist anymore :)
Proposed resolution
Make SqlContentEntityStorageSchemaConverter a slim wrapper around the new API for converting entity type schemas.
Remaining tasks
- make SqlContentEntityStorageSchemaConverter use the new API from #2984782: Add an API for converting entity type schemas to (non-)revisionable/(non-)translatable, with or without data internally
- mark it as deprecated
- rework its test coverage to test the new API instead
User interface changes
Nope.
API changes
Nope.
Data model changes
Nope.