Respond to prediction request with transformed columns

[deliahu]

Description

Add a flag in the api config to add transformed feature values to the prediction response. Or respond with these values automatically (without adding a flag to enable/disable it).

Motivation

Clients may need to perform post-processing on the prediction response based on the values of the transformed features (e.g. entity extraction requires the tokenized text).

Notes

• Add e.g. -r/--raw flag to CLI to show full json response?