Add `#ifdef WITH_ANIM_BAKLAVA` to the blend file reading/writing code, so that the Action layers & slots are ignored when Blender is built without experimental features. This ensures that any loaded Action is just treated as 'legacy' (which is the only kind of Action non-experimental Blender should have to deal with), which will also properly deal with the forward compatible data written by !125065. This fix was committed on the `blender-v4.2-release` branch as 1b7485f20892523942752f81239807b2eab0f00b. Pull Request: https://projects.blender.org/blender/blender/pulls/125068