#6991933 Woop: Domain change warning step

Branched off from #57811

Changes proposed in this Pull Request

• Woop: Add the domain change warning step to the onboarding flow

Fixes #57424

Testing instructions

You need a test site with a business plan on simple infra to begin this flow.

• Go to http://calypso.localhost:3000/start/woocommerce-install/confirm?siteSlug=<your-simple-business-testing-site>
• Confirm you see the domain change warning when you test with a wpcom subdomain.
• Confirm it skips this step when the site has a custom domain