Support RTP cameras with the gstreamer backend

Since many of the many of the machine manufacturers uses low latency RTP digital cameras for operating the vehicles. The digital cameras used follows the ISO 17215 - video communication for road vehicles standard: https://www.iso.org/standard/59433.html

A typical camera for this would be for example:

https://www.orlaco.com/article/orlaco-emos-ethernet-camera-120o

These cameras typically use RTP format for MJPEG or H264 video streams. To display these with hardware acceleration adapted to the embedded device, in Qt5 as a workaround a custom Gstreamer pipeline or integrate the qmlglsink from gstreamer-plugins-good could be used.

For example:

"gst-pipeline: udpsrc port=50004 caps=application/x-rtp,encoding=JPEG,payload=26 ! rtpjpegdepay ! decodebin ! imxvideoconvert_g2d ! autovideosink"

With RTP streams there is no URL that can be entered to receive connect to the camera stream. They only send either unicast to a specific IP address and port number or broadcast on a specific port.

Since in Qt6 we don't want to bring the custom gst-pipelines back as a source property for the mediaplayer, we should provide a means to play RTP streams using the API.