Add .reek.yml

[grodowski]

Starter Reek config file ✨ Let's go through all the warnings from the defaults and check what we might want to override here. The YAML I'm committing now is not finalised!

Once it is finalised, we can configure a pronto-reek Github Action to comment on our PRs. I believe this would make more sense than blocking on pre-push, like we do with Rubocop, because Reek design-oriented warnings may require more effort to fix.

Reek does not support config inheritance, at least until troessner/reek#1512, so I thought we can reuse our config with something like reek -c $(rf-stylez reek-config-path) in the pronto action.

Let's discuss!

[jaytennier]

These all look like reasonable defaults to me. I'm honestly not sure about the values for the max statements/methods/ivar settings but I do like the idea of having them enabled so I guess let's go with those and see if they pose an issue. We can always have this as a non-blocking check for the first little bit to get a feel for them.