task/WG-268: add authentification to backend

[nathanfranklin]

Overview:

Add authentification to backend

Related Jira tickets:

• WG-268

Summary of Changes:

• reworked env variables and there use in settings.py and in docker-compose ymls.
• added auth flow to be used by hazmapper and eventually taggit
• a pre-request check to refresh access token when it's expired or soon-to-be-expired

Testing Steps:

1. To be tested with task/WG-268: add authentification to backend hazmapper#244
2. See task/WG-268: add authentification to backend hazmapper#244 for some testing ideas

Notes:

TODO

• save token/refresh-token in database
• consider that users could be using token not generated with the new auth flow (like they have a JWT but got it from somewhere else)
• handle expiring refresh token. also handle if token needs to be refreshed during task (maybe assume all tasks take 2 hours? and just refresh if going to expire in 2hours?)
• unit tests

[nathanfranklin]

Testing showed we are missing one more fix in addition to 9a8dcdf and b50b100 which need to be cherry-picked into this branch:

    if not self.auth.refresh_token:
AttributeError: 'NoneType' object has no attribute 'refresh_token``

[nathanfranklin]

Testing showed we are missing one more fix in addition to 9a8dcdf and b50b100 which need to be cherry-picked into this branch:

    if not self.auth.refresh_token:
AttributeError: 'NoneType' object has no attribute 'refresh_token``

Done