Centralize nsd associated files

Move all nsd associated files include framework, service and test
to package/Nsd first. After clear all hidden API dependencies, we
can easily migrate these files into connectivity mainline module.

Bug: 206893064
Test: atest FrameworksNetTests CtsNetTestCases
Change-Id: Id26f471a10fe7882e31ccc2dbb73219461f00dbd
diff --git a/packages/Nsd/service/Android.bp b/packages/Nsd/service/Android.bp
new file mode 100644
index 0000000..529f58d
--- /dev/null
+++ b/packages/Nsd/service/Android.bp
@@ -0,0 +1,31 @@
+//
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+package {
+    // See: http://go/android-license-faq
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+filegroup {
+    name: "services.connectivity-nsd-sources",
+    srcs: [
+        "src/**/*.java",
+    ],
+    path: "src",
+    visibility: [
+        "//frameworks/base/services/core",
+    ],
+}