Add content and meta schemas retrieval API endpoints

Context

Following the schema-driven approach, it might be helpful for API users to be able to retrieve json-schema for a specific type.

The idea is to add a schema endpoint for WPC and bulk-data endpoints, which provides json-schema. Also, it is nice to have the possibility to specify if only required fields have to be returned in response.

Scope

1. Add GET: /api/rafs-ddms/v2/samplesanalysis/{analysistype}/data/schema
2. Add schema versioning support via an Accept header, e.g. Accept: application/json; version=1.0.0

Optional:

3. Add optional query parameter requiredOnly=False, which flags whether all or only required properties must be returned.