Add a raw data hash to the model for separate storage mode

Problem/Motivation

When the storage mode for raw data is to use a separate config entity which is owned by the modeler API, we need to make sure that the raw data in that config entity matches the version of the real config entity owner by the model owner.

Proposed resolution

In that save mode, create a hash of the model data and store that with the real model. When loading the config, check the hash and if it doesn't matches, drop the raw data.