rtph264depay: Add prop for flexible nal parsing
requested to merge eric.chandrasekhar/gstreamer-eric-fork:rtph264depay-flexible-nal-parsing into main
This change makes the rtph264depay element more flexible by creating a new option that enables parsing of aggregated NAL units from the incoming RTP stream.
This is done with the addition of a new property, flexible-rtp-nal-aggregation, that defaults to false.
Fixes: gst-plugins-good#982 (moved).