Update Testing with Cypress Lesson

[wvmitchell]

Lesson to be updated: Testing with Cypress

Summary of changes needed:

• Classes are referred to in several places throughout this lesson, this should change to reflect the fact that students will be most familiar with functional React at this point

• Additionally, this lesson needs an overall review, to ensure that it meets our standards, outlined by the lesson creation guidelines below

• We need to add screenshots and/or links to the docs to help students understand how to see whether their network requests are being properly intercepted.

Lesson creation guidelines (also on FE Hub)

• Lesson Preparation Foundations
• 4 Pillars of Remote Instruction
• Instructional Values
• Culturally Responsive Teaching

Additional changes

• Remove class based components from this repo that is used in the lesson
• Update repo to React 18
• Update repo to Router v6
• Refactor as needed based on these updates

[hfaerber]

This ticket has 2 PRs ready for review:

• Updates to the repo used in the lesson are ready for review on this PR
• Updates to the lesson itself are ready for review on this PR