Add NetworkStack app

The app is not started yet, and does not contain any service for now.

Test: built, booted
Bug: b/112869080
Change-Id: Id5a0fd02c891100e85d86b1040e53beec3581950
diff --git a/Android.bp b/Android.bp
index 92c4abe..124f473 100644
--- a/Android.bp
+++ b/Android.bp
@@ -679,6 +679,7 @@
 
     static_libs: [
         "apex_aidl_interface-java",
+        "networkstack-aidl-interfaces-java",
         "framework-protos",
         "android.hidl.base-V1.0-java",
         "android.hardware.cas-V1.0-java",
@@ -818,6 +819,16 @@
     output_extension: "srcjar",
 }
 
+// AIDL interfaces between the core system and the networking mainline module.
+aidl_interface {
+    name: "networkstack-aidl-interfaces",
+    local_include_dir: "core/java",
+    srcs: [
+        "core/java/android/net/INetworkStackConnector.aidl",
+    ],
+    api_dir: "aidl/networkstack",
+}
+
 // Build ext.jar
 // ============================================================
 java_library {