Add EventsExecutor (#161)
Add EventsExecutor (#161)

* Add RMW listener APIs

add constness

Use or discard previous events: Guard conditions

Rename to set_events_executor_callback

Add events support

void return on set_events_executor_callback

Revert "void return on set_events_executor_callback"

Signed-off-by: Alberto Soragna <e595b9615e829905e2aa879232766c66c0896067@irobot.com>

* Remove use_previous_event

Signed-off-by: Mauro Passerino <e67075a9bb29d6683da3ec73e1ad00e71be2b1f9@irobot.com>

* Remove guard condition listener

Signed-off-by: Mauro Passerino <e67075a9bb29d6683da3ec73e1ad00e71be2b1f9@irobot.com>

* refactor to remove listener term

Signed-off-by: William Woodall <c824fe0afe16857dd6f587aa7c4044d2642d60fb@osrfoundation.org>

Co-authored-by: Mauro <e67075a9bb29d6683da3ec73e1ad00e71be2b1f9@irobot.com>
Co-authored-by: William Woodall <c824fe0afe16857dd6f587aa7c4044d2642d60fb@osrfoundation.org>
ros2/rmw_implementation,ros2/rmw_implementation