Advanced Security wizard-style setup dialog for easier GHAS enablement [GA]

### Value Prop

GitHub Advanced Security products will have a guided experience to simplify set up and choose where to enable features. This reduces the prerequisite knowledge required and minimizes friction during setup, making it easier for teams to confidently complete Advanced Security enablement.

### Expected Outcome

GitHub Advanced Security set up will be clearer and more streamlined, reducing complexity, boosting confidence, and helping teams get protected faster.

首先检查 GitHub Advanced Security 的设置流程，以及 issue 所引用的前置知识。payload 未指定任何实现文件、入口点、测试或验收标准，因此请在开始工作前确认向导的预期范围，并定义如何衡量启用成功。

由索引模型根据 Issue 内容生成。