Use Drawer in Settings app

- get rid of PreferenceActivity as much as we can and use fragments instead
- add Drawer widget
- add Dashboard high level entry into the Drawer (but this is work in progress and would be done in another CL)
- add bypass of fragment's Header  validation when launched from the Drawer but *force* validation if external
call thru an Intent

Be aware that WifiPickerActivity should remain for now a PreferenceActivity. It is used by SetupWizard and should
not trigger running the SettingsActivity's header building code. SetupWizard is a Home during the provisionnig process
and then deactivate itself as a Home but would make the Home header to appear in the Drawer (because momentarily we
would have two Home).

Also, verified that:

- the WiFi settings still work when called from SetupWizard
- when you have multiple Launchers, the Home header will appear in the list of Headers in the Drawer

Change-Id: I407a5e0fdd843ad7615d3d511c416a44e3d97c90

src/com/android/settings/wfd/WifiDisplaySettings.java

@@ -42,15 +42,12 @@ import android.os.Looper;
 import android.preference.CheckBoxPreference;
 import android.preference.ListPreference;
 import android.preference.Preference;
-import android.preference.PreferenceActivity;
 import android.preference.PreferenceCategory;
 import android.preference.PreferenceGroup;
 import android.preference.PreferenceScreen;
 import android.provider.Settings;
-import android.text.Html;
 import android.util.Slog;
 import android.util.TypedValue;
-import android.view.Gravity;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -59,14 +56,11 @@ import android.view.View;
 import android.view.View.OnClickListener;
 import android.view.ViewGroup;
 import android.widget.Button;
-import android.widget.CompoundButton;
 import android.widget.EditText;
 import android.widget.ImageView;
-import android.widget.Switch;
 import android.widget.TextView;
 
 import com.android.internal.app.MediaRouteDialogPresenter;
-import com.android.settings.ProgressCategory;
 import com.android.settings.R;
 import com.android.settings.SettingsPreferenceFragment;