AP_camera: Camera tracking example scripts (WIP)

[khanasif786]

This PR realtes to #27773 There are currently two scripts more scripts may be added.

1. send_camera_information send the camera information from companion computer to the FC running Ardupilot over network.
2. the tracking.py scripts runs in parallel thread detecting humans and then sending PITCH YAW commands to FC. You need to specify the gstreamer pipeline command in string format to the example script. By default the example script uses the udp stream. ehich the gstreamer plugin from gazebo uses

[timtuxworth]

Could you use an RTSP stream direct without needing to use gstreamer?

[khanasif786]

@timtuxworth , yeah there are workarounds, just need to catch the rtsp stream and give it to cv2 capture

[srmainwaring]

@khanasif786 - I've rebased this PR on master here: https://github.com/srmainwaring/ardupilot/tree/mav_cmd_camera_example_scripts.

ReadMe.md in this PR must be renamed to README.md before rebasing. This has to be done in a few steps to avoid issues on case insensitive filesystems such as the one used by macOS. The steps are ReadMe.md -> ReadMe_.md -> squash into 2d753992 -> ReadMe_.md -> README.md -> squash, then rebase on master. I tried to force push my branch but don't have permission.

[rmackay9]

A couple of small things:

1. we should squash the commits
2. let's change the README file name to match conventional case
3. resolve merge conflicts at some point