[Tether03] Migrate IpServer into module

Add IpServer which is used to serve ip configuration, dhcp, dns proxy
and nat for downstream interface.

Bug: 136040414
Test: -build, flash, boot
      -atest TetheringTests
      -atest FrameworksNetTests

Change-Id: I23652ae0b9509abe7d38da96d523eb22ab00a343
diff --git a/Tethering/tests/unit/Android.bp b/Tethering/tests/unit/Android.bp
index 089bbd3..da62107 100644
--- a/Tethering/tests/unit/Android.bp
+++ b/Tethering/tests/unit/Android.bp
@@ -43,5 +43,8 @@
     name: "tethering-tests-src",
     srcs: [
         "src/com/android/server/connectivity/tethering/TetheringConfigurationTest.java",
+        "src/android/net/dhcp/DhcpServingParamsParcelExtTest.java",
+        "src/android/net/ip/IpServerTest.java",
+        "src/android/net/util/InterfaceSetTest.java",
     ],
 }