Overview - update UI to use solid color scrim.

Also required updates to colors and status bar icons to match with new
color.

Bug: 179922117
Test: local build and flash on two devices

Change-Id: Ibec54107f52c01f125e6d100abe32434f2067b71
diff --git a/quickstep/res/values/styles.xml b/quickstep/res/values/styles.xml
index df089f6..e56397a 100644
--- a/quickstep/res/values/styles.xml
+++ b/quickstep/res/values/styles.xml
@@ -81,7 +81,7 @@
         parent="@android:style/Widget.DeviceDefault.Button.Borderless">
         <item name="android:textColor">@color/overview_button</item>
         <item name="android:drawableTint">@color/overview_button</item>
-        <item name="android:tint">?attr/workspaceTextColor</item>
+        <item name="android:tint">?android:attr/textColorPrimary</item>
         <item name="android:drawablePadding">8dp</item>
         <item name="android:textAllCaps">false</item>
     </style>