Env-based configuration is not properly functional

[luxaritas]

There's currently some issues with the behavior of using environment variables for package configuration instead of arniefiles.

• IIRC there's some situations where order of checking for or overriding configurations between multiple methods is incorrect (not certain, this may have just been an issue with nupack that I'd fixed)
• IIRC there's some situations where some packages are not supported or not able to be represented via the env var method (missing packages, secondary configuration like envor params locations, multiple versions)

This is probably resolvable by prefixing all arnie-specific environment variables (ie, not options inferred from conventions like NUPACKHOME) so it's something like ARNIE_* so all keys can be looped through like we do with the arniefile