QS visual updates for P

- Black status bar area up top
- Gradient view behind QQS area
- Added stub view for system icon area
- Most things are parameterized for qs_header_system_icons_area_height,
so this can be moved and overlaid for devices with a notch

Test: visual
Bug: 70799006
Bug: 63772836
Change-Id: Iee3a975f50d572084de370d1b183a37f5e8e9e1a
diff --git a/packages/SystemUI/res/layout/qs_customize_panel.xml b/packages/SystemUI/res/layout/qs_customize_panel.xml
index 9ab8ac6..b3b6a0c 100644
--- a/packages/SystemUI/res/layout/qs_customize_panel.xml
+++ b/packages/SystemUI/res/layout/qs_customize_panel.xml
@@ -20,6 +20,7 @@
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="0dp"
+    android:elevation="4dp"
     android:orientation="vertical"
     android:background="@drawable/qs_customizer_background"
     android:gravity="center_horizontal">