Replace JSHint with ESLint shareable config

[ottaviohartman]

Part of https://github.com/AnalyticalGraphicsInc/cesium/pull/5431.

• Add .eslintrc.json files in place of .jshintrc's
• Update the package.json as appropriate
• Add eslint hints where necessary to make sure npm run eslint passes.
• Remove .idea/jsLinters/jshint.xml This is part of an effort to move to shareable configs: https://www.npmjs.com/package/eslint-config-cesium

[mramato]

Thanks!