[Buildstream SDK] New GStreamer patches and add livesync plugin

https://bugs.webkit.org/show_bug.cgi?id=267526

Reviewed by Adrian Perez de Castro.

The livesync is going to be useful for WebRTC. The patches are required for
https://bugs.webkit.org/show_bug.cgi?id=267370 and https://bugs.webkit.org/show_bug.cgi?id=260072.

* Tools/buildstream/elements/freedesktop-sdk.bst:
* Tools/buildstream/elements/sdk-platform.bst:
* Tools/buildstream/elements/sdk/gst-plugin-livesync.bst: Added.
* Tools/buildstream/files/gst-plugin-livesync/Cargo.lock: Added.
* Tools/buildstream/patches/fdo-0001-gstreamer-Additional-patches.patch: Added.

Canonical link: https://commits.webkit.org/273058@main

Tools/buildstream/elements/freedesktop-sdk.bst

@@ -16,6 +16,8 @@ sources:
   path: patches/fdo-0006-gst-plugins-bad-Enable-soundtouch.patch
 - kind: patch
   path: patches/fdo-0009-gst-plugins-bad-Enable-x265-encoder.patch
+- kind: patch
+  path: patches/fdo-0001-gstreamer-Additional-patches.patch
 config:
   options:
     target_arch: '%{arch}'

Tools/buildstream/elements/sdk-platform.bst

@@ -20,6 +20,7 @@ depends:
 - sdk/gst-plugin-audiofx.bst
 - sdk/gst-plugin-closedcaption.bst
 - sdk/gst-plugin-dav1d.bst
+- sdk/gst-plugin-livesync.bst
 - sdk/gst-plugin-rtp.bst
 - sdk/gtk.bst
 - sdk/icecc.bst