feat: Restructure the gst parent<->child relations

gst/src/plugins/autodetect/autovideosink.rs

@@ -1,19 +1,8 @@
-use crate::*;
+use crate::priv_prelude::*;
 
-#[repr(transparent)]
-pub struct AutoVideoSink {
-    inner: gstreamer::Element,
-}
-
-impl IsElement for AutoVideoSink {
-    fn as_element(&self) -> &Element {
-        unsafe { core::mem::transmute(&self.inner) }
-    }
-
-    fn into_element(self) -> Element {
-        Element { inner: self.inner }
-    }
-}
+wrap_gst!(AutoVideoSink, gstreamer::Element);
+parent_child!(Element, AutoVideoSink);
+parent_child!(Bin, AutoVideoSink, downcast);
 
 impl Sink for AutoVideoSink {}