Introducing Clear-all button on Overview

It’s an initial implementation, i.e. no fancy effects.
It shares a parent (LauncherRecentsViewContainer) with RecentsView.
The button is centered in clear_all_button_container, which gets
positioned programmatically to the right of the last task. (RTL polish
will be a separate CL as well).

Bug: 72222505
Change-Id: Ia912908a93a30c2f51450ccf0f97c7495e7916d5
Test: Manual
diff --git a/res/values/config.xml b/res/values/config.xml
index a40afe1..9d1bb41 100644
--- a/res/values/config.xml
+++ b/res/values/config.xml
@@ -147,6 +147,7 @@
     <item type="id" name="search_container_all_apps" />
 
 <!-- Recents -->
+    <item type="id" name="overview_panel"/>
     <integer name="config_recentsMaxThumbnailCacheSize">6</integer>
     <integer name="config_recentsMaxIconCacheSize">12</integer>