Resolve "Add RTP stream support"

What does this MR do?

Adds support for RTP stream on different grabbers

VideoOpenCV/SFrameGrabber

Add a new ffmpeg grabber

How to test it?

(Describe how to test this feature step by step)

Data

(link to the needed data)

Some results

(Some interesting results, screenshot, perfs, ...)

Additional tests to run

(If you need some specific test e.g Windows compilation...)

• Build on Windows
• ...

Associated Issues/Merge Requests

• Issues

  • Fixes repo#number

• Merge requests

  • repo!number