Action client goal ID for cancelGoal

[arsh09]

Description
Hi, thank you for updating the library.

While using the Action class, I noticed that when I want to cancel the goal, I need to set the goal ID but the ID is not a class member of Action. This makes it difficult to cancel specific goal.

Possible Fix

Make goal ID class public member.

[arsh09]

Oh sorry, did not realize that ID is returned on the sendGoal.

[arsh09]

I am unable to cancel the goal from Action.cancelGoal using ROS2 Humble and fibonaci action server.

To demonstrate the bug, please use this fork branch I added two buttons in the ROS2 Action Client example, Send Goal and Cancel Goal.

Small fix: the message interface for /fibonacci is action_tutorials_interfaces/action/Fibonacci which works with feedback and result callback whereas if I use example_interfaces/action/Fibonacci, the action server does not respond with feedback.

Also, I think this suggestion is extremely valuable. The websocket should handle the goal ids which allows for cancellation (or re-subscription) on reconnection, somewhat similar to how it keep track of connected_clients.

I am using the following version of rosbridge-server

[EzraBrooks]

Hi, thanks for this bug report. If you could open a PR with a failing integration test, maybe we could debug it together?