Android close路由问题

Android使用navigation导航框架，是由一个activity和多个fragment组成的页面，flutter页面由fragment包裹。
当flutter调用close时，会调用activity.finish()，关闭当前APP。
能否在INativeRouter中劫持close事件，类似open，由native自定义close的路由管理。

Start with the Android navigation integration and the INativeRouter interface, then compare how open is routed with how Flutter close currently reaches the hosting activity. Trace the activity and fragment behavior described in the issue; done means native code can define close routing without unintentionally finishing the app.

Written by the indexing model from the issue text.