Add video_whole_body_pose_estimation_mapper

[Qirui-jiao]

video_whole_body_pose_estimation_mapper: Input a video containing people, and use the DWPose model to extract the body, hand, feet, and face keypoints of the human subjects in the video, i.e., 2D Whole-body Pose Estimation.

Reference: Effective Whole-body Pose Estimation with Two-stages Distillation (https://github.com/IDEA-Research/DWPose).