chore: create ESLint v8 .eslintrc.js config

[MikeMcC399]

Issue

The configuration for ESLint is defined in package.json eslintrc format. ESLint JSON configurations, including definitions stored in package.json, are deprecated in ESLint v9.

https://github.com/cypress-io/cypress-realworld-app/blob/147d192bae2c5cd9c3cf5540609f23097f3aa08a/package.json#L196-L212

Change

• Move the ESLint configuration from package.json to a new file: .eslintrc.js and convert from JSON to JavaScript format. This is an interim step in preparation for an update to ESLint 9.x.
• Update to eslint@^8.57.0 (final version of ESLint 8.x) in package.json. (This version was already in use in yarn.lock.)

Verification

yarn
yarn eslint .

• Confirm that there are no new failures, not already described in https://github.com/cypress-io/cypress-realworld-app/issues/1547.

[cypress-app-bot]

• Create a Draft Pull Request if your PR is not ready for review. Mark the PR as Ready for Review when you're ready for a Cypress team member to review the PR.

[MikeMcC399]

Withdrawn, as this repo is not ready for migration to ESLint 9, therefore there are no immediate advantages to merging this PR.