#7608257 Woo Tailored Onboarding: Add intro/login and store profiler steps

Proposed Changes

• This PR creates the first two steps for the tailored Woo onboarding flow, namely the intro screen (and subsequent login/signup for a logged out user), followed by the store profiler screen. The latter does not have any persistence logic yet, but does populate all necessary dropdowns.

Testing Instructions

• Check out this branch locally.
• As a logged-in user, navigate to /setup?flow=ecommerce (note that this is a change from the previous name of the flow, which was tailored-ecommerce)
• Verify that you see a welcome screen that appears correctly both on mobile and desktop views:

• Click “Create Your Store” and verify you are taken to a correctly displayed store profiler form:

• Log out of Calypso and go back to /setup?flow=ecommerce
• Verify that as a logged out user, clicking “Create Your Store” navigates you to log in or sign up, after which you are redirected back to the store profiler as expected.

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 #69386