fix: Fixed expiring of goals if events executor is used

[jmachowinski]

This commit is only relevant if the events executor is used.

This commit adds a background thread, to create events for the expire timer of the action.
Without this the action server will not expire old goal results leading to memory and performance issues.

For now, this commit is a draft. There is still a (minor) issue, that the clock used in the background
thread does not work correct in the use_sim_time case (it still runs on system time).

This is an alternative to #2661

In contrast to #2661, it reuses the rcl internal timer and therefore existing code to recompute the
expire times.

@alsora @mauropasse @mjcarroll thoughts ?

[mauropasse]

I don't think creating a new thread per ActionServer is good solution, the TimersManager of the EventsExecutor is already creating a thread to handle timers, so I think that approach should be used.
Threads can be expensive on resource-constrained platforms.
It has been discussed here that maybe the best approach is removing the need for goals to expire, by not having servers storing results.

[jmachowinski]

@mauropasse Note, this is a backport to jazzy. The timer interface is not exposed, therefore there is no way to register a timer at the executor without breaking ABI/API.

[ros-discourse]

This pull request has been mentioned on ROS Discourse. There might be relevant details there:

https://discourse.ros.org/t/next-client-library-wg-meeting-friday-22nd-november-2024/40703/1