add accessibility label for •••

we use "•••" to indicate "other" reactions visually,
however, when visually impaired, eg. screen readers won't have a clue.

therefore, set accessibilityLabel to "Other".

for the other reactions, things might be good enough,
at least, voice over has a chance to read this out in its meaning.
if we get concrete feedback, we'll try to improve.

deltachat-ios/Chat/ChatViewController.swift

@@ -1948,25 +1948,25 @@ extension ChatViewController {
             })
         }
 
-        menuElements.append(
-            UIAction(title: "•••") { [weak self] _ in
-                guard let self else { return }
-                reactionMessageId = self.messageIds[indexPath.row]
+        let action = UIAction(title: "•••") { [weak self] _ in
+            guard let self else { return }
+            reactionMessageId = self.messageIds[indexPath.row]
 
-                let pickerViewController = MCEmojiPickerViewController()
-                pickerViewController.navigationItem.title = String.localized("react")
-                pickerViewController.delegate = self
+            let pickerViewController = MCEmojiPickerViewController()
+            pickerViewController.navigationItem.title = String.localized("react")
+            pickerViewController.delegate = self
 
-                let navigationController = UINavigationController(rootViewController: pickerViewController)
-                if #available(iOS 15.0, *) {
-                    if let sheet = navigationController.sheetPresentationController {
-                        sheet.detents = [.medium(), .large()]
-                        sheet.preferredCornerRadius = 20
-                    }
+            let navigationController = UINavigationController(rootViewController: pickerViewController)
+            if #available(iOS 15.0, *) {
+                if let sheet = navigationController.sheetPresentationController {
+                    sheet.detents = [.medium(), .large()]
+                    sheet.preferredCornerRadius = 20
                 }
-                present(navigationController, animated: true)
             }
-        )
+            present(navigationController, animated: true)
+        }
+        action.accessibilityLabel = String.localized("pref_other")
+        menuElements.append(action)
     }
 
     // context menu for iOS 13+