Create service-connectivity.jar

Create a new target service-connectivity to split
ConnectivityService from services.core.

Add ConnectivityServiceInitializer for initializing
ConnectivityService and add systemReady() in
ConnectivityManager so that SystemServer can call systemReady()
through ConnectivityManager which won't change current behavior.

Bug: 158268939
Test: make target-java, make host-java
      atest FrameworksNetIntegrationTests
      atest FrameworksNetTests
      make, device can boot,
      atest CtsStrictJavaPackagesTestCases
      wifi and mobile data work.
Change-Id: I99401772ba9c1c34adca20040da3c7c72d86ddd9
Merged-In: Ie732bfaf381404af0bb599ca2f421a96e7aa4257
diff --git a/tests/net/Android.bp b/tests/net/Android.bp
index 0fe84ab..cd2dc04 100644
--- a/tests/net/Android.bp
+++ b/tests/net/Android.bp
@@ -59,6 +59,7 @@
         "mockito-target-minus-junit4",
         "net-tests-utils",
         "platform-test-annotations",
+        "service-connectivity",
         "services.core",
         "services.net",
     ],