Demand-Gen: Dev Onboarding Landing

Created by: zlonko

This closes #5320 (closed). It adds the gated page Developer Onboarding and abstracts the homepage's feature walkthrough into a component.

Reference: Figma and meta

Changelog

• Adds better-dev-onboarding
• Creates a FeatureWalkthrough component
• Creates featureCopy to store common copy

Notes

• I appreciate any feedback on the component/copy implementation! Want to make sure I am following our team's preferred pattern here.
• The Figma calls for text CTAs in the walkthrough. I kept the button styling for consistency with the homepage, because the copy and layout are otherwise identical.
• The Figma specifies a different responsiveness for BlogResourceItem on mobile: two columns with a small image. This is consistent across other wireframes, but it is not used on Prod. I went with the Prod pattern here. Are we looking to update the mobile design for BlogResourceItem to the one shown in Figma?

Test

1. Navigate to /better-dev-onboarding
2. Please check that the design matches the Figma on desktop and mobile
3. Please check that the homepage remains consistent with FeatureWalkthrough implemented
4. Ensure linting passes.
5. Ensure prettier has standardized the proposed changes.
6. Ensure dev and production builds work.