chore: replace angular-devkit/build-angular with ngtools/webpack

Author: SvetoslavTsenov

package.json

@@ -36,7 +36,7 @@
     "nativescript-dev-typescript": "^0.4.6",
     "typescript": "~2.7.2",
     "nativescript-dev-webpack": "next",
-    "@angular-devkit/build-angular": "~0.7.0-rc.0"
+     "@ngtools/webpack": "6.1.0-rc.0"
   },
   "scripts": {
     "u": "update-ns-webpack",