Data types with no implementation should error out explicitly
Currently, when the selected runtime doesn't have an implementation for a certain data type the compiler bails out leaving a cryptic message. For example, if AnyType is needed when using the cpp_stl runtime, the compiler fails with the following message:
`AnyType (of class io.kaitai.struct.datatype.DataType$AnyType$)`

It would be good for the UX to have a compiler error informing the user that the data type needed is not implemented in the chosen runtime.