added vertical scrollbar for chat list for desktop

apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/views/chat/ChatView.kt

@@ -1005,6 +1005,14 @@ fun BoxWithConstraintsScope.ChatItemsList(
       }
     }
   }
+  if (appPlatform.isDesktop) {
+    VerticalScrollbar(
+      modifier = Modifier.align(Alignment.CenterEnd)
+        .fillMaxHeight(),
+      adapter = rememberScrollbarAdapter(listState),
+      reverseLayout = true
+    )
+  }
   FloatingButtons(chatItems, unreadCount, chat.chatStats.minUnreadItemId, searchValue, markRead, setFloatingButton, listState)
 }