Get rid of pixl_config.yml

[milanmlft]

Attempt to reduce complexity by:

• Removing pixl_config.yml and moving the useful bits to .env (which already largely had the information contained in pixl_config.yml)
• Move the APIConfig class to cli._config
• Reduce the use of the name config, to avoid confusion and in preparation of Support configuration for multiple projects #309

Motivation: in #309 we will add config.yml files to configure how projects should be run through the pipeline. The information contained in those config.yml files are completely different from what is in the current pixl_config.yml file, which may lead to some confusion. In addition, the information in pixl_config.yml is already encoded in the .env environment variables anyway.

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To do

• Check that system test still succeeds
• Remove all references to pixl_config.yml in the docs
• Document the appropriate way of configuring the EHR and Imaging APIs with the new env variables

[stefpiatek]

Works on GAE. What's more fun is that if you're using the environment then it can be done from any directory if you've used pip install -e. Which I think is okay, or do we want it to read the config only from the directory that the cli is initiated in?

[milanmlft]

or do we want it to read the config only from the directory that the cli is initiated in?

I would say it's fine, not much chance that there would be any name clashes for these environment variables.

[stefpiatek]

I would say it's fine, not much chance that there would be any name clashes for these environment variables.

Only risk is if you use the environment for the wrong project. e.g. I'm in dev but I use the test environment. Agree that I think its fine

[stefpiatek]

🎉