fix(router): 修复线程池静态初始化导致主线程死锁ANR

[Firefly822]

在一些机型上，会出现anr的问题，优化下线程池的初始化，懒加载一些变量

java.util.concurrent.locks.ReentrantLock.newCondition (ReentrantLock.java:537)
java.util.concurrent.LinkedBlockingDeque. (LinkedBlockingDeque.java:163)
com.therouter.TheRouterThreadPool. (TheRouterThreadPool.kt:61)
com.therouter.flow.Digraph.beforeInit (Digraph.java:62)
com.therouter.TheRouter.init (TheRouter.java:80)
com.therouter.TheRouter.init (TheRouter.java:73)
com.therouter.InnerTheRouterContentProvider.onCreate (InnerTheRouterContentProvider.kt:23)
android.content.ContentProvider.attachInfo (ContentProvider.java:2669)
android.content.ContentProvider.attachInfo (ContentProvider.java:2637)
android.app.ActivityThread.installProvider (ActivityThread.java:8490)
android.app.ActivityThread.installContentProviders (ActivityThread.java:8003)
android.app.ActivityThread.handleBindApplication (ActivityThread.java:7667)
android.app.ActivityThread.-$$Nest$mhandleBindApplication (unavailable)
android.app.ActivityThread$H.handleMessage (ActivityThread.java:2505)
android.os.Handler.dispatchMessage (Handler.java:107)
android.os.Looper.loopOnce (Looper.java:232)
android.os.Looper.loop (Looper.java:317)
android.app.ActivityThread.main (ActivityThread.java:8927)
java.lang.reflect.Method.invoke (Native method)
com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:681)
com.android.internal.os.ZygoteInit.main (ZygoteInit.java:915)