launcher3: Gate strict mode enablement behind flag.

Bug: 394651876
Flag: com.android.launcher3.enable_strict_mode
Test: Manual
Change-Id: I973dacbfac1fbcd889c503623df948c8fde379dd
diff --git a/aconfig/launcher.aconfig b/aconfig/launcher.aconfig
index 9fa2f50..ed370ec 100644
--- a/aconfig/launcher.aconfig
+++ b/aconfig/launcher.aconfig
@@ -601,3 +601,10 @@
     purpose: PURPOSE_BUGFIX
   }
 }
+
+flag {
+  name: "enable_strict_mode"
+  namespace: "launcher"
+  description: "Enable Strict Mode for the Launcher app"
+  bug: "394651876"
+}