This will enable parameter files to store the net as an ONNX bytestream, or as an LWTNN json file.
- Clear up the TODOs listed in the IS_FastCaloSimEvent dir. Mostly they are suggesting smart pointers.
- Clean up the class names. Mine are idiosyncratic.
- Check it runs on ONNX files (irrespective of the fact that we haven't quite nailed the conversion to ONNX yet).
- Check that the ONNX session isn't copying the byte stream.
- Check building param files still works fine.
- Run clang-tidy.