Split feedback_pipeline into multiple files and added a config manager

[Fan]

Splitting up the feedback_pipeline into multiple files.

I kept the current feedback_pipeline.py file as the main entry point for the program. The new files will probably undergo a lot more changes as we implement other changes and features. This is probably a good start to a bigger refactor.

[yselkowitz]

For starters, the imports in the test_*.py files need to be updated for this restructuring; that's why CI is currently failing.

I'm not quite sure what the consequences of having a feedback_pipeline.py script and a feedback_pipeine/__init__.py in the same directory might be (wrt import feedback_pipeline), although that should only affect the tests (we're not designing this as a library).

As for the contents of the restructuring, this will take longer to review, but let's start with fixing the CI.

[yselkowitz]

Testing this locally.

[yselkowitz]

So far this looks fine in local testing, but as it will require manual intervention on the running instance, let's hold off on merging it until we're both around.