Add OEM_PAID capability to system api

Some system apps should be able to request OEM_PAID networks.  This
makes a lot of sense when Android is used as in-vehicle infotainment
systems.

Bug: 68762530

Test: runtest -x frameworks/base/tests/net/ -c android.net.NetworkCapabilitiesTest

Change-Id: Ic916de7522a9f803a2410bc4e3e82101fd9d0dbd

core/java/android/net/NetworkCapabilities.java

@@ -17,6 +17,7 @@
 package android.net;
 
 import android.annotation.IntDef;
+import android.annotation.SystemApi;
 import android.net.ConnectivityManager.NetworkCallback;
 import android.os.Parcel;
 import android.os.Parcelable;
@@ -276,6 +277,7 @@ public final class NetworkCapabilities implements Parcelable {
      * this network can be used by system apps to upload telemetry data.
      * @hide
      */
+    @SystemApi
     public static final int NET_CAPABILITY_OEM_PAID = 22;
 
     private static final int MIN_NET_CAPABILITY = NET_CAPABILITY_MMS;