feat: put the access codes behind a feature flag

config/packages/flagception.yaml

@@ -0,0 +1,10 @@
+# See full configuration at https://github.com/bestit/flagception-bundle
+#
+# Features are off unless an environment says otherwise: a deployment that knows nothing about a
+# flag gets the state the feature had before it existed. Switching one on is an .env change, not
+# a release.
+flagception:
+    features:
+        access_codes:
+            default: false
+            env: FEATURE_ACCESS_CODES