Rename NetworkStack package

Set the new name to com.android.networkstack. Also rename the stub APK
to com.android.networkstack.permissionstub.

Also add shared UID to the NetworkStackPermissionStub to enforce
signature restrictions on the UID.

Test: booted, WiFi working
Bug: 124033493
Change-Id: Id8967db08b7faaa659b20f86f1013493eb0e188f
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index ac55bfa..11a01ed 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -17,7 +17,7 @@
  */
 -->
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
-          package="com.android.mainline.networkstack"
+          package="com.android.networkstack"
           android:sharedUserId="android.uid.networkstack">
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />