Enable strict concurrency for BCNLoginNavigationController

Summary:
Enable strict concurrency for `BCNLoginNavigationController`.

Let's embrace Swift 6 syntax :)

This case is easy since the whole `BCNLoginNavigationController` is on main actor.

Differential Revision: D60809973

fbshipit-source-id: 53745fcfbfb63895d224344de6e5063eb67cea7d

Source/IGListKit/IGListAdapterUpdateListener.h

@@ -33,6 +33,7 @@ typedef NS_ENUM(NSInteger, IGListAdapterUpdateType) {
 /**
  Conform to this protocol to receive events about `IGListAdapter` updates.
  */
+NS_SWIFT_UI_ACTOR
 NS_SWIFT_NAME(ListAdapterUpdateListener)
 @protocol IGListAdapterUpdateListener <NSObject>