Add support for showing border for desktop tile

When a external keyboard is connected and ENABLE_KEYBOARD_QUICK_SWITCH
feature flag is enabled, we highlight the selected tile in overview.
Add support to the new desktop tile to show the highlight.

Bug: 269342116
Test: connect an external keyboard, use alt+tab to open overview and
  switch between the tiles
Change-Id: I29ac5864776a9a251ecdb0cb4b741b12747de564
diff --git a/quickstep/res/layout/task_desktop.xml b/quickstep/res/layout/task_desktop.xml
index 96aabb4..2ec9d4c 100644
--- a/quickstep/res/layout/task_desktop.xml
+++ b/quickstep/res/layout/task_desktop.xml
@@ -17,12 +17,15 @@
 
 <com.android.quickstep.views.DesktopTaskView
     xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:androidprv="http://schemas.android.com/apk/prv/res/android"
+    xmlns:launcher="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:clipChildren="true"
     android:clipToOutline="true"
     android:defaultFocusHighlightEnabled="false"
-    android:focusable="true">
+    android:focusable="true"
+    launcher:borderColor="?androidprv:attr/colorAccentSecondaryVariant">
 
     <View
         android:id="@+id/background"