Pin unlock : hides behind feature flag (disabled by default)

libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlags.kt

@@ -49,4 +49,10 @@ enum class FeatureFlags(
         description = "Send and receive voice messages",
         defaultValue = false,
     ),
+    PinUnlock(
+        key = "feature.pinunlock",
+        title = "Pin unlock",
+        description = "Allow user to lock/unlock the app with a pin code or biometrics",
+        defaultValue = false,
+    ),
 }