action_sheet: Use ZulipIcons.link instead of Icons.link

Author: sm-sayedi

lib/widgets/action_sheet.dart

@@ -1023,7 +1023,7 @@ class CopyMessageTextButton extends MessageActionSheetMenuItemButton {
 class CopyMessageLinkButton extends MessageActionSheetMenuItemButton {
   CopyMessageLinkButton({super.key, required super.message, required super.pageContext});
 
-  @override IconData get icon => Icons.link;
+  @override IconData get icon => ZulipIcons.link;
 
   @override
   String label(ZulipLocalizations zulipLocalizations) {

test/widgets/action_sheet_test.dart

@@ -1573,8 +1573,8 @@ void main() {
       });
 
       Future<void> tapCopyMessageLinkButton(WidgetTester tester) async {
-        await tester.ensureVisible(find.byIcon(Icons.link, skipOffstage: false));
-        await tester.tap(find.byIcon(Icons.link));
+        await tester.ensureVisible(find.byIcon(ZulipIcons.link, skipOffstage: false));
+        await tester.tap(find.byIcon(ZulipIcons.link));
         await tester.pump(); // [MenuItemButton.onPressed] called in a post-frame callback: flutter/flutter@e4a39fa2e
       }