ARouter support scan external dex/class to collect router

[act262]

In this scene , while I'm using like HotSwap , then put patch dex to external position to hold those file, ARouter did not has a way to load external dex/class to collect external router. ARouter only scan origin apk and multidex . So, in my case , we need a interface to load our other dex to make ARouter working well.