multimedia/gstreamer1-plugins-v4l2 MidnightBSD

## Summary - synchronize GStreamer core, base/bad/good/ugly plugin bundles, Rust and Python bindings, editing services, libav, RTSP server, Qt bindings, and related plugin ports at 1.28.6 - refresh 1.28 Meson compatibility patches, plists, and generated Rust crate metadata - reset all coupled port revisions to 0 and add the new svt-av1 plugin mapping - retain gstreamer-vaapi at its last available 1.26.1 release because upstream no longer publishes a 1.28 vaapi tarball ## Validation - core: `bmake makesum patch build fake package test check-license` passed - base plugin bundle: all 368 compile targets passed serially with introspection disabled - default plugin introspection is blocked on this host because the GI scanner links the still-installed 1.26 allocator during the build-tree …

`textproc/libxml2` 2.15 changed SONAME from `libxml2.so.2` to `libxml2.so.16` **and** removed ELF symbol versioning entirely — the new library defines no `LIBXML2_*` versions at all. Consumers built against the old library were never rebuilt, so they still record a dependency on `libxml2.so.2` plus version requirements nothing can satisfy, and fail at load time: ``` ld-elf.so.1: /usr/local/lib/libxml2.so.2: version LIBXML2_2.4.30 required by /usr/local/lib/libevdocument3.so.4 not defined ``` ### Scope `Tools/scripts/bump_revision.pl -f -l textproc/libxml2` — **436 Makefiles**: 323 revisions incremented, 113 gained a `PORTREVISION` line. The diff touches nothing but `PORTREVISION` lines (verified: `git diff -U0` shows no other changed line), and spot-checked ports still …