Remove cordovaPlatforms and cordovaPlugins from package.json

ionic state was removed from Ionic 3 CLI. From the documentation:

The plugins and platforms can be managed entirely by Cordova. Please remove the cordovaPlatforms }}and {{cordovaPlugins keys from your package.json file. If you're using Cordova 7, please review the announcement about how Cordova uses config.xml and package.json to manage plugins and platforms.