multimedia/gstreamer1-plugins-rust: Update to 0.15.1

Changes:
https://gstreamer.freedesktop.org/releases/1.28/#1.28.1

Security:	791d4b29-19fb-11f1-87cc-e73692421fef

The y4menc (previously from good) and y4mdec (previously from bad)
plugins have been consolidated into y4m (now from good).

The vaapi component (multimedia/gstreamer1-vaapi) is no longer supplied
by upstream and will be removed after 2026Q1. This has been superseded by
the va plugin from 'bad', which we don't have and is rather Linux-heavy,
but no ports seem to use this anyways. Remove from makesum-all target
and adjust to be static 1.26.10 (last available) version.

Add svtav1 component to gstreamer.mk after f96400339bd6. [1]

multimedia/gstreamer1-plugins-svt-hevc has been marked DEPRECATED since
multimedia/svt-hevc is marked DEPRECATED and will be removed after
2026Q1. [1] This port does not seem to be used anywhere in the ports
tree.

Note for local patching: meson_options.txt was renamed by upstream to
meson.options across the board [2] and this change adapts to that.

Changes:
https://gstreamer.freedesktop.org/releases/1.28/

[2] https://gitlab.freedesktop.org/gstreamer/gstreamer/-/commit/128710caab3e7521384c4c82df031702f1728af8

PR:		292706 [1]
Reported by:	jbeich [1]

https://gstreamer.freedesktop.org/releases/1.26/

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

PR:		269895
Exp-run by:	antoine
Sponsored by:   Serenity Cybersecurity, LLC

Reported by:	jbeich
Fixes:	88a2a7b867abff10d848f12dea00e2fa3e21a319

PR:		261585
Reviewed by:	riggs,jbeich,tcberner

Differential Revision:	https://reviews.freebsd.org/D36850

- The spc plugin was removed inflavor for the gsm plugin.
- Added in tree qt plugin.

Changelog: https://gstreamer.freedesktop.org/releases/1.16/#1.16.2

Update net-im/fractal to 4.2.2 to support GStreamer 1.16 (approved by maintainer)

Thanks to antoine@ for the exp-run.

PR:		239386

PR:		231406
Submitted by:	Greg V <greg@unrelenting.technology>
Exp-run by:	antoine
Approved by:	portmgr (antoine)

Rework the adding of dependancies in Mk/bsd.gstreamer.mk.
Previous when using USE_GSTREAMER[1] it would just add the request modules to BUILD/RUN_DEPENDS. This caused the qa script to complain because the old code didn't implicit depend on the gstreamer1 and gstreamer1-plugins[-bad] ports for the libraries they carried, even if they where present via the plugins! The new code adds implicit depends on these ports so USE_GSTREAMER[1] using ports have all the libraries included.

* The mad mp3 plugin was removed, mpg123 plugin also provides mp3 decoding. Switch over ports that used the gstreamer1 mad plugin.
* gtksink plugin renamed -> gtk
* Hook up the sndio plugin into the framework
* Add some indirect dependacies where needed
* Reorder the plugin list in bsd.gstreamer.mk so only one plugin per line. When changing plugins it doesn't result in multiple lines being changed.
* Remove mentions in bsd.gstreamer.mk of plugins mentions that where removed.
* Depend on libunwind on i386/amd64, GStreamer links to it if it is present.

PR:		220753
Exp-run by:	antoine@