Add bindings for GstControlBinding and related API
https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstControlBinding.html and https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstControlSource.html in core, and some GstObject API.
Plus a new crate for https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer-libs/html/gstreamer-control.html:
- Add a Gir_Gst*.toml and autogenerate all relevant types, see https://github.com/gtk-rs/gir/
- Make sure the autogenerated code is correct, add manual code as needed
- Write manual bindings for anything that can't be automatically generated (macros, miniobjects, ...)
- Add src/lib.rs for re-exporting, Cargo.toml, etc