Dupe BluetoothSettings and DeviceListPreferenceFragment

Create the obsolete version of the belowing fragments, so we could
flip between old page and new page.

BluetoothSettingsObsolete and DeviceListPreferenceObsoleteFragment
contains all the old logic but:
1. Logic about BluetoothPairingPreferenceController(ag/2239482),
since this preference shouldn't be checked in without the flag :(

This cl also adds logic in MasterSwitchPreferenceController to flip
these two pages.

Following cl will refactor these fragment to make it compatible
to new framework.

Bug: 35877041
Test: RunSettingsRoboTests
Change-Id: I1cc1bc2d49d8a3e11c3127e56f6409fbc84028d8

res/xml/bluetooth_settings_obsolete.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2017 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.
+-->
+
+<PreferenceScreen
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:title="@string/bluetooth_settings" >
+
+</PreferenceScreen>