Refactor SDK checkout error handling

[orzechdev]

I want to merge this change because it changes checkout error handling.
Additionally, to simplify sdk, I have changed names from CheckoutRepositoryManager to LocalStorageManager and from NetworkManager to ApolloClientManager.

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Pull Request Checklist

1. All visible strings are translated with proper context.
2. All data-formatting is locale-aware (dates, numbers, and so on).
3. The changes are tested.
4. The code is documented (docstrings, project documentation).
5. Changes are mentioned in the changelog.

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[krzysztofwolski]

Besides one comment LGTM

[krzysztofwolski]

LGTM.

@dominik-zeglen please confirm if requested changes are fine

[dominik-zeglen]

Why untyping it?
I wonder if it wouldn't be better (it'll be certainly easier) if we'd drop one level of nesting, simplifying this type to Record<"setCartItem" | "setPromoCode", boolean>

[orzechdev]

Yes, it might be typed, but it is not easy thing to do for me as it is not simple typing - I wrote string, because I didn't want to always redefine this type to be consistent with available methods in job classes.
And I'm not sure if dropping one level would good idea, because, what if we will have the same method name in two different job classes?