Create a way to customize ng-new

### Command

new

### Description

for workshops it would be helpful to have a customized start screen with custom html to make it easier for people to start the workshop and have less friction with updated start view with newer versions as e.g. with v17 happened

### Describe the solution you'd like

a configuration which provides a reference to a custom template of a start screen, e.g.

ng new todo-list --start=@ng-girls/starter

and for this there need to be a special scheme to configure the start template or other options

### Describe alternatives you've considered

stackblitz, but I would also have it with the CLI

Commencez par le point d’entrée de la commande ng new et déterminez comment les options de commande et la configuration du projet sont définies. L’exemple de l’issue est ng new todo-list --start=@ng-girls/starter ; l’implémentation doit inclure un schéma défini pour sélectionner un modèle de démarrage personnalisé et clarifier les options de configuration prises en charge.

Rédigé par le modèle d'indexation à partir du texte de l'issue.