Stepper: Spike on domains step

[escapemanuele]

Proposed Changes

This is just a test to see whether it is possible to bring the Domains step from /start to Stepper.

Things missing:

• We still save step result with submitSignupStep and rely on the dependency store. This could be brought to the onboarding store, but I think it will need work on plans and checkout step as well. This can be maybe thought as an intermediate step?
• use-your-domain page (/start/newsletter/domains/use-your-domain). Rendered based on stepSectionName, shouldn't be difficult to integrate.
• Management of queryObject, should be easy to get values from url params. Values have been set to default values for testing.

Testing Instructions

Pre-merge Checklist

• [ ] Have you written new tests for your changes?
• [ ] Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• [ ] Have you checked for TypeScript, React or other console errors?
• [ ] Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• [ ] Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?

Related to #

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[escapemanuele]

Work is here https://github.com/Automattic/wp-calypso/pull/68722