Instructor Dashboard - Implement Content Groups V2 JSON API

[brianjbuck-wgu]

The current Content Groups endpoint (/group_configurations/{course_key}) returns HTML with embedded JSON data, making it difficult to use programmatically and not following REST API best practices.

Current Issues:

• Returns text/html content type with embedded JSON
• Tightly coupled to Backbone.js frontend rendering
• Not RESTful or properly documented
• Difficult to consume by external clients or MFEs
• Hard to generate OpenAPI/Swagger documentation

Current Endpoint:

• GET/POST /group_configurations/{course_key}

[feanil]

@brianjbuck-wgu I know that the CourseGroupConfigurationsView currently only has a GET endpoint, why not just add a post endpoint to the existing API? The change would be additive and so should not require a new version of the API?