env var to set loglevel for python logging

Is there a way to set the `loglevel` through an env var?
This would be especially useful for lambda-docker.
We would like to be able to filter out a lot of noise and only see our app logs, at least during development.

The issue does not name a file, test, or entry point. Start by locating the emulator's logging configuration and environment-variable handling, then verify that the requested variable changes the log level and filters development output without suppressing application logs.

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