Add cypress and cypress-axe packages for accessibility testing (#7201)

[heybran]

Description

Add cypress and cypress-axe packages to do automatic accessibility testing.

Related GitHub issue(s)

#7201

Testing instructions

1. Run npm run cypress:open
2. Cypress will be open for us to run cypress tests

Screenshots / screencast

Changelog text for these changes

Enhancement: Pods now has cypress installed to do automatic accessibility testing. #7201 (@heybran)

PR checklist

• I have tested my own code to confirm it works as I intended.
• My code follows the WordPress Coding Standards.
• My code follows the WordPress Inline Documentation Standards.
• My code includes automated tests for PHP and/or JS (if applicable).

[what-the-diff]

PR Summary

• Configured Cypress Setup
  An additional file, cypress.config.js, has been established to provide custom configurations for setting up Cypress.

• Provided Setup Instructions
  A README.md file was added to give guidance on how to arrange a cypress.env.json file.

• Cypress Testing for Edit Pod Screen
  Five separate Cypress tests were developed to ensure the functionality and accessibility of the edit pod screen. They check the addition of a field, the creation of a new group, and verify there are no accessibility violations.

• Cypress Testing for Manage Pods Screen
  A new Cypress test, cypress/e2e/manage-pods-screen/manage-pods-screen.cy.js, was composed to test for accessibility violations on the manage pods screen.

• Accessibility Reports
  Cypress accessibility reports are documented and compiled in a new file, cypress/e2e/reports.md.

• Sample Data
  A fixture file, cypress/fixtures/example.json, has been added which encompasses sample data for testing purposes.

• Custom Login Command
  A new commands file cypress/support/commands.js has been created that hosts a custom login command for Cypress.

• Setting Up for Accessibility Tests
  We've uploaded a new support file, cypress/support/e2e.js. It imports the commands.js file and sets up cypress-axe to conduct accessibility exams.

• Updated package.json
  Introduced new scripts cypress:open in package.json to enable opening of the Cypress test runner.

[sc0ttkclark]

Can we move the /cypress/ directory into /tests/cypress/?

[heybran]

I've tried, but can't make it work as cypress has specific rules. I can close this PR and keep the cypress on my local repo since I don't think anyone else other than me will be needing cypress.

[sc0ttkclark]

Is there a corresponding GitHub action we should be using here?