Improving code base and creating config file

• Using npx to create project
• Config file config.js added to project

Updating code to latest version of ESRI ArcGIS JS API

• v4 - 4.6
• v3 - 3.23

Updating ESRI app js code

Optimizing code for App.js based on esri-loader latest documentation

Project code reorganization

Project code is reorganization to store map and view information inside react store.

Added capability to choose an ESRI API version

• Creating ESRI React App now supports Progressive Web Apps by default
• Added capability to choose an ESRI API version

$ create-esri-react-app esri_app --api 3

ESRI API v4 is now default