Fix T97408: Temporary fix for attribute convert undo

Sculpt undo now detects if an attribute layer has
changed type/domain and unconverts it back.  This
is a temporary workaround to a more fundamental
bug in the undo system.

Memfile undo assumes it can always rebuild the
application state from the prior undo step,
which isn't true with incremental undo systems.

The correct fix is to push an extra undo step prior
to running an operator if an incremental undo system
is active and the operator is using memfile undo.

source/blender/editors/include/ED_geometry.h

@@ -7,12 +7,22 @@
 
 #pragma once
 
+#include "BKE_attribute.h"
+#include "DNA_customdata_types.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-void ED_operatortypes_geometry(void);
+struct Mesh;
 
+void ED_operatortypes_geometry(void);
+bool ED_geometry_attribute_convert(struct Mesh *mesh,
+                                   const char *layer_name,
+                                   CustomDataType old_type,
+                                   AttributeDomain old_domain,
+                                   CustomDataType new_type,
+                                   AttributeDomain new_domain);
 #ifdef __cplusplus
 }
 #endif