Support Union Types in Tapir

[pme123]

At the moment it is not possible to use Union Types in Tapir
The following Code does not work:

case class In(
      subStatusKey: SubStatusKeyDocuments | SubStatusKeyGeneral = SubStatusKeyDocuments.`documents-prepared`,
     )
object In:
    given Schema[In] = Schema.derived
    given CirceCodec[In] = deriveCodec
end In

enum SubStatusKeyGeneral derives ConfiguredEnumCodec:
  case canceled
  case finished

object SubStatusKeyGeneral:
  given Schema[SubStatusKeyGeneral] = Schema.derivedEnumeration[T].defaultStringBased
end SubStatusKeyGeneral
...

Expectations

• If there are Schemas for all of the Union Types, this should work out of the box, otherwise throw an exception which of the types are missing the Schema.
• The output should look be 'oneOf' the types.