Fix Bluetooth device details crash on screen rotation

We were getting the following exception when you rotated the Bluetooth
device details screen:

java.lang.RuntimeException: Unable to start activity
ComponentInfo{com.android.settings/com.android.settings.SubSettings}:
java.lang.IllegalStateException: This Activity already has an action bar
supplied by the window decor. Do not request Window.FEATURE_ACTION_BAR
and set android:windowActionBar to false in your theme to use a Toolbar
instead.

It turns out that allowing EntityHeaderController to inflate the
settings_entity_header.xml view seems to cause this - if you instead
manually include a LayoutPreference and hand that to
EntityHeaderController, you don't have the problem.

The rotation failure couldn't be tested with Robolectric because our
version doesn't support using FragmentTestUtil.startFragment for
fragments which use PreferenceScreen's ("sorry, not yet
implemented"). So instead this includes an app test.

Bug: 62447414
Test: runtest --path=BluetoothDeviceDetailsRotationTest.java
Change-Id: I8d052d1f4ab6e2b0ca5c0e513ec366bdcc382d99