#12507440 New Instructions step: initial approach to UI for the new instructions screen

Related to #89760

Proposed Changes

This is a rough mockup for the new instructions screen. This PR does not intend to be the final screen but something to help us iterate on the design of this screen. It’s worth mentioning that it is behind the feature flag, so it can be merged as-is anytime.

The idea is to get this merged so we can start hooking up the real behaviour.

The state of the actions is hardcoded via a timer, this behaviour will change sooner or later to reflect the actual state of affairs.

This is what it currently looks like:

Testing Instructions

• Apply this diff or go to the calypso live link below
• Go through /start flow
• Once you get to the Goals page run this in your console sessionStorage.setItem('flags', "migration-flow/remove-processing-step") and reload the page
• Select the import intent
• Keep going until the instructions screen
• Make sure you don’t see the processing screen
• Make sure you see a new step (4.) that conveys a list of pending actions
• The list is still hardcoded so no progress will be seen
• Verify you see an animation as the list gets completed

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• https://wpcalypso.wordpress.com/devdocs/docs/testing/index.md 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)?
• For changes affecting Jetpack: Have we added the “[Status] Needs Privacy Updates” label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?