Underline links when button shapes accessibility setting is on

Tusker/Views/ContentTextView.swift

@@ -78,10 +78,21 @@ class ContentTextView: LinkTextView, BaseEmojiLabel {
         linkTextAttributes = [
             .foregroundColor: UIColor.tintColor
         ]
+        updateLinkUnderlineStyle()
         
         // the text view's builtin link interaction code is tied to isSelectable, so we need to use our own tap recognizer
         let recognizer = UITapGestureRecognizer(target: self, action: #selector(textTapped(_:)))
         addGestureRecognizer(recognizer)
+        
+        NotificationCenter.default.addObserver(self, selector: #selector(updateLinkUnderlineStyle), name: UIAccessibility.buttonShapesEnabledStatusDidChangeNotification, object: nil)
+    }
+    
+    @objc private func updateLinkUnderlineStyle() {
+        if UIAccessibility.buttonShapesEnabled {
+            linkTextAttributes[.underlineStyle] = NSUnderlineStyle.single.rawValue
+        } else {
+            linkTextAttributes.removeValue(forKey: .underlineStyle)
+        }
     }
     
     // MARK: - Emojis