Create an POST API endpoint to set data in the json_context table.

[chuang-CE]

There needs to be a new API endpoint that allows callers to upload a json_context object in the json_context table. The API should take a URL and a json blob necessary that are necessary to create a json_context object. This API should only be called by a System Admin, and only once during initial setup of the Registry. Make sure to include this endpoint in Swagger. We need this endpoint so we reduce the security risk of having to access URLs outside of a contained environment.