SQL Server: bring JSON type out of experimental status #36024
Description
EF 9.0 brought experimental support for the Azure SQL JSON data type (#32150, Azure SQL docs), which is still in preview. As the Azure SQL support will go GA soon, we need to bring the feature out of experimental status and do any necessary polishing/test coverage/fixing up.
Note that we have tests for the JSON data type, but we don't actually execute them in CI, since there's no on-premise version of SQL Server that supports the type yet. SQL Server 2025 is supposed to go into public preview soon, so at that point we should be able to run tests against it (e.g. via docker on Linux). We should also make sure that current test coverage is sufficient.
As the recommended way to represent JSON would be the new JSON data type, we should consider allowing people to always do that, rather than to have to manually configure this every time (#34416). However, on older SQL Server versions the type doesn't exist yet.