New Settings preference for One Handed mode

Add toggles in Settings location:
Settings > System > Gesture > One-Handed

Bug: 151130376

Test: manual check Settings > System > Gesture > One-Handed
Test: make RunSettingsRoboTests ROBOTEST_FILTER=
      "com.android.settings.gestures.OneHandedSettingsTest"
Test: make RunSettingsRoboTests ROBOTEST_FILTER=
      "com.android.settings.gestures
      .OneHandedAppTapsExitPreferenceControllerTest"
Test: make RunSettingsRoboTests ROBOTEST_FILTER=
      "com.android.settings.gestures
      .OneHandedEnablePreferenceControllerTest"
Test: make RunSettingsRoboTests ROBOTEST_FILTER=
      "com.android.settings.gestures
      .OneHandedTimeoutPreferenceControllerTest"
Test: make RunSettingsRoboTests ROBOTEST_FILTER=
      "com.android.settings.gestures.OneHandedSettingsUtilsTest"

Change-Id: Iafbd3ad051ff0f9c2f4a1b6fcacdccc137b65d0c

src/com/android/settings/gestures/OneHandedEnablePreferenceController.java

@@ -0,0 +1,49 @@
+/*
+ * 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.gestures;
+
+import android.content.Context;
+
+import com.android.settings.core.BasePreferenceController;
+import com.android.settings.core.TogglePreferenceController;
+
+/**
+ * The controller to handle one-handed mode enable or disable state.
+ **/
+public class OneHandedEnablePreferenceController extends TogglePreferenceController {
+
+    public OneHandedEnablePreferenceController(Context context, String key) {
+        super(context, key);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        return BasePreferenceController.AVAILABLE;
+    }
+
+    @Override
+    public boolean setChecked(boolean isChecked) {
+        OneHandedSettingsUtils.setSettingsOneHandedModeEnabled(mContext,
+                isChecked);
+        return true;
+    }
+
+    @Override
+    public boolean isChecked() {
+        return OneHandedSettingsUtils.isOneHandedModeEnabled(mContext);
+    }
+}