feat(ui): add onAttachmentTap to ImageGroup

packages/stream_chat_flutter/lib/src/image_group.dart

@@ -15,6 +15,7 @@ class ImageGroup extends StatelessWidget {
     required this.size,
     this.onReturnAction,
     this.onShowMessage,
+    this.onAttachmentTap,
   }) : super(key: key);
 
   /// List of attachments to show
@@ -23,6 +24,9 @@ class ImageGroup extends StatelessWidget {
   /// Callback when attachment is returned to from other screens
   final ValueChanged<ReturnActionType>? onReturnAction;
 
+  /// Callback when attachment is tapped
+  final void Function(Message message, Attachment attachment)? onAttachmentTap;
+
   /// Message which images are attached to
   final Message message;
 
@@ -117,6 +121,10 @@ class ImageGroup extends StatelessWidget {
     BuildContext context,
     int index,
   ) async {
+    if (onAttachmentTap != null) {
+      return onAttachmentTap!(message, images[index]);
+    }
+
     final channel = StreamChannel.of(context).channel;
 
     final res = await Navigator.push(

packages/stream_chat_flutter/lib/src/message_widget.dart

@@ -133,6 +133,7 @@ class MessageWidget extends StatefulWidget {
                       messageTheme: messageTheme,
                       onShowMessage: onShowMessage,
                       onReturnAction: onReturnAction,
+                      onAttachmentTap: onAttachmentTap,
                     ),
                   ),
                   border,