Feature request

Feature description

Add support for ON_REQUESTED_INCOMPATIBLE_QOS and ON_OFFERED_INCOMPATIBLE_QOS events. This will enable rclcpp/rclpy make client callbacks regarding incompatible QoS events, which are when participants on the same topic are discovered but are unable to connect due to QoS policy incompatibilities.

This is required to complete feature request ros2/ros2#822.

Implementation considerations

Extend PubListener and SubListener to respond to on_requested_incompatible_qos and on_offered_incompatible_qos callbacks respectively. Also, make the relevant changes to guard conditions for events and takeNextEvent().

However, a successful implementation of this feature is blocked by eProsima/Fast-DDS#852.