e2e: migrate to flat config

Using npx @eslint/migrate-config .eslintrc.json
Then add the additional packages needed
(@eslint/compat, globals, @eslint/eslintrc, @eslint/js)
Add paths from the .gitignore file to the ignored patterns.
Remove the options from the call to eslint which are not
supported anymore in the package.json.

The resulting schema of the command
node_modules/.bin/eslint --print-config specs/login.cy.js > eslint-config-js.json
is different.
But diffing only the rules seemed to look the same.

Issue: ecamp#5282