Update 3rd-party modules - .eslintrc to eslint.conf.js (flat config)

The new ‘flat config’ (eslint.conf.js) can be used with ESLint v8.  To make it easier to upgrade eslint to v9, upgrade .eslintrc.js to the equivalent ‘flat config’, eslint.conf.js. 

If we have time to do it for in this upgrade we can, however, this can be done later with no problems. 
