refactor: move PlayFlags defaults into Playbin3 and clean up unused prelude imports

gst/src/plugins/playback/playbin3.rs

@@ -1,4 +1,5 @@
 use crate::priv_prelude::*;
+use playback::PlayFlags;
 
 wrap_gst!(Playbin3, gstreamer::Element);
 parent_child!(Element, Playbin3);
@@ -80,3 +81,15 @@ impl Playbin3 {
         self
     }
 }
+
+impl Playbin3 {
+    pub fn default_flags() -> PlayFlags {
+        PlayFlags::SOFT_COLORBALANCE
+            | PlayFlags::DEINTERLACE
+            | PlayFlags::BUFFERING
+            | PlayFlags::SOFT_VOLUME
+            | PlayFlags::TEXT
+            | PlayFlags::AUDIO
+            | PlayFlags::VIDEO
+    }
+}