Keyguard/Shade migration - Add aconfig flag for NSSL

Bug: 278054201
Test: N/A
Flag: ACONFIG keyguard_shade_migration_nssl DEVELOPMENT
Change-Id: Icc4943e1c982000e07af27182e8b7f950a320a83
diff --git a/packages/SystemUI/aconfig/systemui.aconfig b/packages/SystemUI/aconfig/systemui.aconfig
index c274911..a9027de 100644
--- a/packages/SystemUI/aconfig/systemui.aconfig
+++ b/packages/SystemUI/aconfig/systemui.aconfig
@@ -66,3 +66,11 @@
     description: "Adds haptic feedback to the brightness slider."
     bug: "296467915"
 }
+
+flag {
+    name: "keyguard_shade_migration_nssl"
+    namespace: "systemui"
+    description: "Moves NSSL into a shared element between the notification_panel and "
+        "keyguard_root_view."
+    bug: "278054201"
+}