Add userExperienceIterationTwo feature flag utility

Added a FeatureFlags utility class to manage feature toggling within the application. This initial commit introduces a flag for the userExperienceIterationTwo feature, allowing for controlled testing and phased rollout as development progresses. The flag can be manually adjusted as needed.

frontend/lib/utils/feature_flags.dart

@@ -0,0 +1,3 @@
+class FeatureFlags {
+  static const bool userExperienceIterationTwoEnabled = false;
+}