Migrate robolectric tests to junit tests

This change do the 2 things:

1. Add new junit tests files which replace robolectric
   RobolectricTestRunner & RuntimeEnvironment with
   AndroidX objects without problem.
2. Remove the robolectric test files which have it's new junit files.

This change migrate 103 files, there are still 1209
files to go.

Bug: 174728471
Test: atest
      make RunSettingsRoboTests
Change-Id: I15ed3f4745b85862f720aabbf710ce1475aced93

tests/unit/src/com/android/settings/vpn2/VpnUtilsTest.java

@@ -0,0 +1,42 @@
+/*
+ * 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.vpn2;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import android.net.ConnectivityManager;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@RunWith(AndroidJUnit4.class)
+public final class VpnUtilsTest {
+    @Test
+    public void testIsAlwaysOnVpnSet() {
+        final ConnectivityManager cm = mock(ConnectivityManager.class);
+        when(cm.getAlwaysOnVpnPackageForUser(0)).thenReturn("com.example.vpn");
+        assertThat(VpnUtils.isAlwaysOnVpnSet(cm, 0)).isTrue();
+
+        when(cm.getAlwaysOnVpnPackageForUser(0)).thenReturn(null);
+        assertThat(VpnUtils.isAlwaysOnVpnSet(cm, 0)).isFalse();
+    }
+}