2023-01-04 | auth: Add `/register-user` endpoint...* gn3/app.py: register top-level error handlers. reorganise oauth2 blueprint.
* gn3/auth/__init__.py: reorganise oaut2 blueprint.
* gn3/auth/authentication/oauth2/views.py: reorganise oauth2 blueprint.
* gn3/auth/authorisation/exceptions.py -> gn3/auth/authorisation/errors.py
* gn3/auth/authorisation/groups.py: rename file/module
* gn3/auth/authorisation/resources.py: rename file/module
* gn3/auth/authorisation/views.py: Add `/register-user` endpoint
* gn3/auth/blueprint.py: reorganise oauth2 blueprint.
* gn3/errors.py: register top-level error handlers.
| Frederick Muriuki Muriithi |