Before it was the job of the ng-add schematic to save the package. Now we do
it automatically. This is more expected (and works without ng-add schematics
if the user want to use "ng add moment" for example).
Does not show a better error if there are schematics but ng-add isnt found. That will
simply show "schematics ng-add not found" or something alike, which is fine here.
fixes#10467
