Add bottom right chip to dream overlay to show glanceable hub

This is added temporarily behind a flag for UX testing purposes and is
not intended to be a proper, full implementation.

Chip can be moved to the bottom left, replacing the home controls
button, by changing the system setting
open_hub_chip_replace_home_controls to 1.

Bug: 339667383
Test: N/A
Flag: com.android.systemui.glanceable_hub_shortcut_button
Change-Id: I34ef11c5d764ca46aea074b14d19f2ac804e3941
diff --git a/packages/SystemUI/aconfig/systemui.aconfig b/packages/SystemUI/aconfig/systemui.aconfig
index 36bad5e..cb9e6aa 100644
--- a/packages/SystemUI/aconfig/systemui.aconfig
+++ b/packages/SystemUI/aconfig/systemui.aconfig
@@ -990,6 +990,13 @@
 }
 
 flag {
+  name: "glanceable_hub_shortcut_button"
+  namespace: "systemui"
+  description: "Shows a button over the dream and lock screen to open the glanceable hub"
+  bug: "339667383"
+}
+
+flag {
   name: "glanceable_hub_gesture_handle"
   namespace: "systemui"
   description: "Shows a vertical bar at the right edge to indicate the user can swipe to open the glanceable hub"