core: Re-unify on one OSTREE_OBJECT_TYPE_FILE

Having the archived vs not distinction in the object system wasn't
useful in light of pack files.  In fact, we should probably move
towards generating a pack file per commit by default.

src/libotutil/ot-variant-utils.h

@@ -69,6 +69,8 @@ gboolean ot_util_variant_from_stream (GInputStream         *src,
                                       GCancellable         *cancellable,
                                       GError              **error);
 
+GInputStream *ot_variant_read (GVariant             *variant);
+
 G_END_DECLS
 
 #endif