fix(build): set other @Esri/arcgis-rest-js-* pacakges as external

AFFECTS PACKAGES:
@esri/arcgis-rest-auth
@esri/arcgis-rest-common-types
@esri/arcgis-rest-feature-service
@esri/arcgis-rest-geocoder
@esri/arcgis-rest-groups
@esri/arcgis-rest-items
@esri/arcgis-rest-request

ISSUES CLOSED: #128

rollup.config.umd.js

@@ -54,6 +54,7 @@ export default {
   context: "window",
   extend: true, // causes this module to extend the global specified by `moduleName`
   moduleName,
+  external: packageNames,
   globals,
   plugins: [
     typescript(),