chore: Add ddm-ui feature flag (#56379)

src/sentry/conf/server.py

@@ -1388,6 +1388,8 @@ SENTRY_FEATURES = {
     "organizations:crons-new-onboarding": False,
     # Enable usage of customer domains on the frontend
     "organizations:customer-domains": False,
+    # Delightful Developer Metrics (DDM): Enable sidebar menu item and all UI (requires custom-metrics flag as well)
+    "organizations:ddm-ui": False,
     # Enable the 'discover' interface.
     "organizations:discover": False,
     # Enables events endpoint rate limit

src/sentry/features/__init__.py

@@ -239,6 +239,7 @@ default_manager.add("organizations:custom-symbol-sources", OrganizationFeature,
 default_manager.add("organizations:dashboards-basic", OrganizationFeature, FeatureHandlerStrategy.INTERNAL)
 default_manager.add("organizations:dashboards-edit", OrganizationFeature, FeatureHandlerStrategy.INTERNAL)
 default_manager.add("organizations:data-forwarding", OrganizationFeature, FeatureHandlerStrategy.INTERNAL)
+default_manager.add("organizations:ddm-ui", OrganizationFeature, FeatureHandlerStrategy.REMOTE)
 default_manager.add("organizations:discover-basic", OrganizationFeature, FeatureHandlerStrategy.INTERNAL)
 default_manager.add("organizations:discover-query", OrganizationFeature, FeatureHandlerStrategy.INTERNAL)
 default_manager.add("organizations:dynamic-sampling", OrganizationFeature, FeatureHandlerStrategy.INTERNAL)