TF-145 Implement LoadMoreEmails in ThreadView

core/lib/presentation/state/success.dart

@@ -16,6 +16,20 @@ class UIState extends ViewState {
 class LoadingState extends UIState {
   LoadingState();
 
+  @override
+  List<Object?> get props => [];
+}
+
+class LoadingMoreState extends UIState {
+  LoadingMoreState();
+
+  @override
+  List<Object?> get props => [];
+}
+
+class RefreshingState extends UIState {
+  RefreshingState();
+
   @override
   List<Object?> get props => [];
 }