Feature/add open api

My goal here was to provide a generic setup of the swagger open-api schema rendering using drf-spectacular which could be a good API documentation for every developers (front or back) working on their own instances.

It provides schema explanations and even a way to test requests. Would be interesting to configure it to secure the access to the documentation in any way, or distinguish public/authenticated endpoints, and support DPOP authentication.

Available at https://server.com/docs/, example available here https://api.test2.startinblox.com/docs/, looks like it when deployed:

What do you think ?