Reader Onboarding: Add "Step 2" Initial Styling

[DustyReagan]

Related to https://github.com/Automattic/loop/issues/188

Proposed Changes

• This PR adds the initial styling for the "Step 2" modal
• It also disables "Step 2" on the banner if "Step 1" (following 3 or more tags) is not completed.

Before	After

Why are these changes being made?

• Push Reader Onboarding project forward.

Testing Instructions

• Go to /read?flags=reader/onboarding
• Click on step 2 of the onboarding banner
• View the new sytyling

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• 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)?
• 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)?

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-122030

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-122030&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-122030&env=a8c-for-agencies

[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• notifications
• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug add/style-to-discover-sites on your sandbox.

[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

Sections (~111 bytes added 📈 [gzipped])

name    parsed_size           gzip_size
reader       +617 B  (+0.1%)     +111 B  (+0.0%)

Sections contain code specific for a given set of routes. Is downloaded and parsed only when a particular route is navigated to.

Legend

What is parsed and gzip size?

Parsed Size: Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory.
Gzip Size: Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.

[a8ci18n]

This Pull Request is now available for translation here: https://translate.wordpress.com/deliverables/16913804

Some locales (Hebrew, Japanese) have been temporarily machine-translated due to translator availability. All other translations are usually ready within a few days. Untranslated and machine-translated strings will be sent for translation next Monday and are expected to be completed by the following Friday.

Thank you @DustyReagan for including a screenshot in the description! This is really helpful for our translators.