Publish Keypoints (2D) from Tracked Images as ROS Topic

[shabpompeiano]

Overview This PR introduces a new feature that enables orb_slam3_ros to retrieve keypoints from tracked images (2D pixel coordinates) and subsequently publishes them as a ROS topic (as PointCloud2, where z is 0 for each point). This enhancement is aimed at providing external modules with access to keypoints for various applications such as enhanced post-processing, analytics, or other vision tasks.

Changes

• Extended the internal functions of ORB-SLAM3 to capture and store keypoints from tracked images.
• Integrated a new ROS publisher within the orb_slam3_ros node to broadcast these keypoints on /orb_slam3/tracked_key_points topic.

[thien94]

This is awesome @shabpompeiano . Thank you greatly for your work. Looks good to me.