refactor: rename wn component to match file name (#490)

Author: josefinalliende

lib/ui/contact_list/chat_list_screen.dart

@@ -423,7 +423,7 @@ class _ChatListScreenState extends ConsumerState<ChatListScreen> with TickerProv
                 left: 0,
                 right: 0,
                 child:
-                    WnStickyHeadsUp(
+                    WnHeadsUp(
                       title: 'No Relays Connected',
                       subtitle: 'The app won\'t work until you add at least one.',
                       action: InkWell(

lib/ui/core/ui/wn_heads_up.dart

@@ -4,8 +4,8 @@ import 'package:gap/gap.dart';
 import 'package:whitenoise/ui/core/themes/assets.dart';
 import 'package:whitenoise/ui/core/themes/src/app_theme.dart';
 
-class WnStickyHeadsUp extends StatelessWidget {
-  const WnStickyHeadsUp({
+class WnHeadsUp extends StatelessWidget {
+  const WnHeadsUp({
     super.key,
     required this.title,
     required this.subtitle,