IDPF-92 Added redis, updated config files, added support for dbt-platform

[0RWilliams]

Updated Identity service with support for Redis, and DBT-Platform.
As part of the work to get this service deployed i have added:

• dbt-copilot-python for checking the environment and setting up the database connections
• dj-database-url for mapping the database connection string
• replaced redis_url with IDENTITY_REDIS_URL and IDENTITY_REDIS to match dbt-terraform parameters.

I have also created a prod.py config file, and updated manage.py to default to prod.py ready for deployment.

Added Typing to config files (Not sure if we should go down this route, or if it's overkill)
Moved all Env declarations to the top of the file. (discussion point)

*Downgraded waitress to 2.1.2 as we had problems with this upgrade on several other services.

[marcelkornblum]

Overall it's good.

Personally I'm not a fan of the settings file ordering, and while I approve of typing, I think it's overkill in the settings myself :)