[Testing] To migration DefaultSubscriptionControllerTest

1. Use AndroidJunit4 instead of RobolectricTestRunner
2. Use ApplicationProvider instead of RuntimeEnvironment to get context
3. Change Copy Right
4. Create new class and add a function which loads the Settings Resource.
5. remove getOnPreferenceChangeListener. Becasue the error:
java.lang.NoSuchMethodError: No virtual method getOnPreferenceChangeListener()

Bug: 173004787
Test: atest -c DefaultSubscriptionControllerTest
Change-Id: Iac9834f2a47bd8b50234646197a31058ffacaa4b

tests/unit/src/com/android/settings/testutils/Utils.java

@@ -0,0 +1,28 @@
+/*
+ * 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 com.android.settings.testutils;
+
+import android.content.Context;
+
+public final class Utils {
+    public static int getResourceId(Context context, String type, String name) {
+        return context.getResources().getIdentifier(name, type, context.getPackageName());
+    }
+
+    public static String getResourceString(Context context, String name) {
+        return context.getResources().getString(getResourceId(context, "string", name));
+    }
+}