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

从 ng new 命令的入口点开始，确定命令选项和项目配置是如何定义的。Issue 中的示例是 ng new todo-list --start=@ng-girls/starter；完成的实现应包含用于选择自定义起始模板的明确定义方案，并明确支持的配置选项。

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