Support a properties-file (available during runtime) for ml-models (Stateless evaluation in container)

[pinankg]

Hello Vespa Team,
Can you please consider support a properties-file which is available during run-time along with the model ? So some meta-data e.g. threshold/label, etc can be associated with the model.
This is for the stateless evaluation of the models like (XGBoost, TensorFlow, Onnx, etc) which is supported in vespa.

Thank you,
Pinank