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

Start with the ng new command entry point and determine how command options and project configuration are defined. The issue's example is ng new todo-list --start=@ng-girls/starter; done should include a defined scheme for selecting a custom start template and clarify the supported configuration options.

Written by the indexing model from the issue text.