Refactor RoutingCoordinator

- This CL puts RoutingCoordinator into staticlibs to make it usable by
both Tethering and ConnectivityService on R.
- This CL also changes the return type of
  ConnectivityInternalApi#getRoutingCoordinatorManager() to IBinder so
  it has fewer dependencies.

Bug: 350699020
Test: CI

Change-Id: Iba096e940795cd33e61c5141721394ad39e5ce6d
diff --git a/staticlibs/tests/unit/Android.bp b/staticlibs/tests/unit/Android.bp
index 3186033..91f94b5 100644
--- a/staticlibs/tests/unit/Android.bp
+++ b/staticlibs/tests/unit/Android.bp
@@ -27,6 +27,7 @@
         "net-utils-device-common-ip",
         "net-utils-device-common-struct-base",
         "net-utils-device-common-wear",
+        "net-utils-service-connectivity",
     ],
     libs: [
         "android.test.runner",