Refactor Footer, Navbar, and PricingModal to class components

[sweep-nightly]

Description

This PR refactors the Footer, Navbar, and PricingModal components from functional components to class components in order to align with the requirements of the issue #435. The refactoring involves changing the syntax and structure of the components to use class-based components in React.

Summary

• Refactored the Footer component into a class component named Footer.
• Moved the JSX returned by the Footer function into the render method of the Footer class.
• Refactored the Navbar component into a class component named Navbar.
• Moved the JSX returned by the Navbar function into the render method of the Navbar class.
• Refactored the PricingModal component into a class component named PricingModal.
• Moved the JSX returned by the PricingModal function into the render method of the PricingModal class.

Please review and merge these changes. Thank you!

Fixes #435.

---

To checkout this PR branch, run the following command in your terminal:

git checkout sweep/refactor-class-components_5

---

🎉 Latest improvements to Sweep:

• Use Sweep Map to break large issues into smaller sub-issues, perfect for large tasks like "Sweep (map): migrate from React class components to function components"
• Getting Sweep to format before committing! Check out Sweep Sandbox Configs to set it up.
• We released a demo of our chunker, where you can find the corresponding blog and code.

---

💡 To get Sweep to edit this pull request, you can:

• Leave a comment below to get Sweep to edit the entire PR
• Leave a comment in the code will only modify the file
• Edit the original issue to get Sweep to recreate the PR from scratch

[netlify]

✅ Deploy Preview for papaya-pothos-8db6ca ready!

Name	Link
🔨 Latest commit	cb82b43
🔍 Latest deploy log	https://app.netlify.com/sites/papaya-pothos-8db6ca/deploys/64ed58086a12d900080ee111
😎 Deploy Preview	https://deploy-preview-439--papaya-pothos-8db6ca.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[netlify]

✅ Deploy Preview for sweepdev ready!

Name	Link
🔨 Latest commit	cb82b43
🔍 Latest deploy log	https://app.netlify.com/sites/sweepdev/deploys/64ed58081c03d4000853c51a
😎 Deploy Preview	https://deploy-preview-439--sweepdev.netlify.app/
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.