Add systemserverclasspath_fragments property to apex.

- All contents of the fragment are added as java_lib dependencies.
- Generated classpaths.proto is added into etc as required.

Bug: 180105615
Test: m nothing
Change-Id: I8e8e8b019c4ca2909182f205a47deffa946de6da
diff --git a/apex/Android.bp b/apex/Android.bp
index e234181..14c8771 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -32,6 +32,7 @@
         "apex_test.go",
         "bootclasspath_fragment_test.go",
         "platform_bootclasspath_test.go",
+        "systemserver_classpath_fragment_test.go",
         "vndk_test.go",
     ],
     pluginFor: ["soong_build"],