Better setup for `ng new` - Use existing schematic from Angular before adding {N}

[d-koppenhagen]

Is your feature request related to a problem? Please describe.

Currently the ng new schematic will almost setup a new Angular App by itself with files and templates, the Angular CLI internal schematics are already be able to create itself. This can cause slightly differences when trying to support a new major version and manual default workspace changes in the Angular CLI has to be added to the nativescript ng new schematic as well.

See:

• https://github.com/NativeScript/nativescript-schematics/tree/master/src/ng-new/application/_files
• https://github.com/NativeScript/nativescript-schematics/tree/master/src/ng-new/shared/_files

Describe the solution you'd like Instead of having a copy of all needed files in this project, the nativescript ng new schematic should just execute the Angular CLIs internal ng new schematic and then just change what's needed for adding {N} to the project.