[Feature Request] Allow Deep Links validation tool to support flavors (not only `lib/main.dart` entry point)

The [tool](https://docs.flutter.dev/tools/devtools/deep-links) for validating deep links does not allow to specify an entry point for the app other than the default one (`lib/main.dart`). If I have flavors with multiple main files (such as `main_development.dart`, `main_staging.dart`, etc), which is a common case in many applications, particularly enterprise ones, I'm not able to use the tool.

从链接文档中描述的 deep-links 验证工具开始，跟踪它当前如何选择 lib/main.dart。确定相关的实现和测试，然后将完成标准设为能够选择并验证特定 flavor 的入口点，例如 main_development.dart。

由索引模型根据 Issue 内容生成。