onscreen/native: Set default color encoding and range values

In order to ensure consistent behavior with the composited path as well as across
different KMS drivers. In the future we'll want to use other values as well,
requested by client via the upcoming color representation protocol.

Note that right now KMS drivers default to different values. Most use BT709 and
narrow range, notably Intel and AMD, but some others do not.

BT709/narrow is arguably a much better default than BT601/narrow  as the former is
used for most contemporary video content and the later more for still images.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4204>

src/backends/native/meta-onscreen-native.c

@@ -462,6 +462,32 @@ apply_transform (MetaCrtcKms            *crtc_kms,
                                       hw_transform);
 }
 
+static void
+apply_color_encoding (MetaKmsPlaneAssignment *kms_plane_assignment,
+                      MetaKmsPlane           *kms_plane)
+{
+  if (!meta_kms_plane_is_color_encoding_handled (kms_plane,
+                                                 META_KMS_PLANE_YCBCR_COLOR_ENCODING_BT709))
+    return;
+
+  meta_kms_plane_update_set_color_encoding (kms_plane,
+                                            kms_plane_assignment,
+                                            META_KMS_PLANE_YCBCR_COLOR_ENCODING_BT709);
+}
+
+static void
+apply_color_range (MetaKmsPlaneAssignment *kms_plane_assignment,
+                   MetaKmsPlane           *kms_plane)
+{
+  if (!meta_kms_plane_is_color_range_handled (kms_plane,
+                                              META_KMS_PLANE_YCBCR_COLOR_RANGE_LIMITED))
+    return;
+
+  meta_kms_plane_update_set_color_range (kms_plane,
+                                         kms_plane_assignment,
+                                         META_KMS_PLANE_YCBCR_COLOR_RANGE_LIMITED);
+}
+
 static MetaKmsPlaneAssignment *
 assign_primary_plane (MetaCrtcKms            *crtc_kms,
                       MetaDrmBuffer          *buffer,
@@ -501,6 +527,8 @@ assign_primary_plane (MetaCrtcKms            *crtc_kms,
                                                    *dst_rect,
                                                    flags);
   apply_transform (crtc_kms, plane_assignment, primary_kms_plane);
+  apply_color_encoding (plane_assignment, primary_kms_plane);
+  apply_color_range (plane_assignment, primary_kms_plane);
 
   return plane_assignment;
 }