Allow configuration of Kotlin render style

[chiroptical]

The Kotlin rendering style we use here doesn't exist in Aeson (https://hackage.haskell.org/package/aeson-2.0.1.0/docs/Data-Aeson-TH.html#t:SumEncoding). There is a PR for this haskell/aeson#828.

We should add another rendering style to more closely match Aeson's TaggedObject style.

• Add failing golden tests for TaggedObject style
• Get test passing for Sum in SOP
• Get test passing for Product in SOP
• Add more golden tests to ensure nothing else is broken

Notes:

• This implementation is not ideal. It should be configurable per type but going to continue here to get a clear implementation
• The tests are incredibly unwieldy right now. It would be nice to have some TH that generates the golden tests with names that match the golden files