Add public fields to NetworkScore and make it @SystemApi

Bug: 113554781
Bug: 146583853
Test: FrameworksNetTests
Change-Id: I19d965c0146196cb67b3417eb1790ccd90ce3233
diff --git a/core/java/android/net/NetworkScore.aidl b/core/java/android/net/NetworkScore.aidl
new file mode 100644
index 0000000..be9a98b
--- /dev/null
+++ b/core/java/android/net/NetworkScore.aidl
@@ -0,0 +1,19 @@
+/**
+ * Copyright (c) 2020, 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 android.net;
+
+parcelable NetworkScore;