validate_json_schema() function

[SarahJohnsonONS]

validate_json_schema() added with tests. Function accepts schema as str, and data to be validated against schema as str or dict. Users can also include an optional msg (str) and specify the integer value to indent json output.

TODO: Write README once function is approved.

[mikeAdamss]

few comments but this is mostly there

[mikeAdamss]

minor comments

[mikeAdamss]

Will this work as if error_msg is None or indent is None: to allow default kwargs of None?

My thinking is, I think this all makes sense and won't interfere with things, but we don't 100% know until we get into structured logs and the like, so I'm keen for a default behaviour of exactly what jsonschema usually does (so its obvious to a DE how to turn off the prettiness if they need to).

[SarahJohnsonONS]

Yup, this works - json.dumps default for indent is None.

[mikeAdamss]

LGTM 👍