gstreamer1-plugins-aom

Mk/Uses/gstreamer.mk:
- Sort, fix whitespace issues and typos
- Promote several common variables to improve maintainer QOL
*   There's now no need to set manually set PORTVERSION nor
    SOVERSION in several Makefiles
*   This will help to prevent not updating some components
*   A note has been added, however, to remind maintainers
    to remake distinfo for certain ports
- Improve documentation

multimedia/gstreamer1-plugins-webrtc:
- New port split from multimedia/gstreamer1-plugins-bad
- multimedia/gstreamer1-plugins-rust has been updated
  to reflect this change

net/gstreamer1-plugins-sctp:
- New port split from multimedia/gstreamer1-plugins-bad

x11-toolkits/gstreamer1-plugins-qt5:
- Moved here from graphics/gstreamer1-plugins-qt to
  align with its new Qt6 counterpart

x11-toolkits/gstreamer1-plugins-qt6:
- New port: GStreamer Qt6 QML videosink plugin

*/*:
- Improve Makefile order and formatting
- Sorry for the repo churn, but not fixing this would just lead to more
  poorly formatted gstreamer ports in the future via copypasta

https://gstreamer.freedesktop.org/releases/1.24/#1.24.8

PR:		278914
Reported by:	vvd