Implement API Errors based on new specs

[Monstarrrr]

Blocking

• Centralize API Errors handling #219
• Add error responses to API docs #220

Problem

We should not return error messages in a different structure for api/ (our custom routes) than it is being returned in auth/ (djoser).

Solution

We preferably need to return errors in one single coherent format.
So we either reproduce the same structure as how djoser handles errors, or we override djoser's

https://www.django-rest-framework.org/api-guide/exceptions/#custom-exception-handling

The drf-standardized-errors package provides an exception handler that generates the same format for all 4xx and 5xx responses. It is a drop-in replacement for the default exception handler and allows customizing the error response format without rewriting the whole exception handler. The standardized error response format is easier to document and easier to handle by API consumers.

Integration with drf-spectacular
https://drf-standardized-errors.readthedocs.io/en/latest/openapi.html

Based on:

• Ignore this issue #278

We should override djoser's errors