Refactor Pipeline peripherals

[tstadel]

Proposed changes:

• move config helper methods to new module pipelines.config
• move CodeGen and EvalReportGen to new module pipelines.utils
• disassemble to_code tests into get_config and CodeGen tests
• fix missing Pipeline import in to_code
• decouple peripherals from actual Pipeline class, interfaces are pipeline_config or networkx graph
• use networkx for dependency processing

Status (please check what you already did):

• First draft (up for discussions & feedback)
• Final code
• Added tests

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[ZanSara]

Great improvements! Also very happy about the tests 🤩 I left a few comments for some improvements here and there, but mostly minor stuff.

I just wished I was more explicit when I said where exactly I was going to mess with the Pipeline loading and validation part, because these changes are going to result in a hot mess of merge conflicts with my Pipeline validation PR 🥲 I'd rather merge yours first, mine is not ready yet: but I might need some help to deal with the damage later 😂

[ZanSara]

LGTM 👍 Just learned about the match parameter of pytest.raises(), I'm going to make use of it!