Implement new homepage design

What does this MR do and why?

Implements the new homepage design! 🎨

• Design issue: Reorganize content in docs.gitlab.com home page (technical-writing#854 - closed) • Pedro Moreira da Silva • 16.10
• Implementation issue: Implement homepage redesign (#1740 - closed) • Sarah German

Figma file: https://www.figma.com/file/e6ahJYABbB1sPT1k5s8HBp/Reorganize-docs-home-technical-writing%23854?node-id=2395%3A2469&mode=dev

Screenshots, screen recordings, or links to review app

Review app: https://1740-homepage-redesign-gps.docs.gitlab-review.app/

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Configure a local GitLab Docs environment: https://gitlab.com/gitlab-org/gitlab-docs/-/blob/main/doc/setup.md.
2. Compile and run the site: make view
3. Visit the homepage: http://127.0.0.1:3000/

Merge request acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this merge request.

Closes #1740 (closed)