When deleting multiple messages, inform the user of the number

taken from #2263 by @ianmacd

_locales/en/messages.json

@@ -94,7 +94,7 @@
   "messageDeletionForbidden": "You don’t have permission to delete others’ messages",
   "deleteJustForMe": "Delete just for me",
   "deleteForEveryone": "Delete for everyone",
-  "deleteMessagesQuestion": "Delete those messages?",
+  "deleteMessagesQuestion": "Delete $count$ messages?",
   "deleteMessageQuestion": "Delete this message?",
   "deleteMessages": "Delete Messages",
   "deleted": "Deleted",

stylesheets/_session_conversation.scss

@@ -91,7 +91,7 @@
   .selection-mode {
     .messages-container > *:not(.message-selected) {
       animation: toShadow $session-transition-duration;
-      opacity: 0.40;
+      opacity: 0.4;
     }
   }
 }

ts/interactions/conversations/unsendingInteractions.ts

@@ -336,13 +336,14 @@ export async function deleteMessagesByIdForEveryone(
     await Promise.all(messageIds.map(m => getMessageById(m, false)))
   );
 
-  const moreThanOne = selectedMessages.length > 1;
+  const messageCount = selectedMessages.length;
+  const moreThanOne = messageCount > 1;
 
   window.inboxStore?.dispatch(
     updateConfirmModal({
       title: window.i18n('deleteForEveryone'),
       message: moreThanOne
-        ? window.i18n('deleteMessagesQuestion')
+        ? window.i18n('deleteMessagesQuestion', [messageCount.toString()])
         : window.i18n('deleteMessageQuestion'),
       okText: window.i18n('deleteForEveryone'),
       okTheme: SessionButtonColor.Danger,