This allows forward declaring `OpCallContext`, avoiding the transitive include `WM_Types.hh` in `UI_interface_layout.hh` Pull Request: https://projects.blender.org/blender/blender/pulls/141804
This allows forward declaring `OpCallContext`, avoiding the transitive include `WM_Types.hh` in `UI_interface_layout.hh` Pull Request: https://projects.blender.org/blender/blender/pulls/141804