Inter / intra dependency specification and resolution mechanism for marketplace plugins

Need to have a dependency model for plugins. We should be able to specify dependent plugins for a plugin in a marketplace. The dependencies can be inter or intra marketplace. We need to have a mechanism for specifying and automatically installing dependencies of a plugin.

Claude code has this support already and we need something like this in copilot-cli

https://code.claude.com/docs/en/plugin-dependencies

从链接的 Claude plugin-dependencies 文档开始，找到 copilot-cli 中现有的 marketplace 插件规范和安装入口。将 marketplace 之间及 marketplace 内部的依赖行为以及自动安装定义为完成标准。