Expose ULandscapeLayerInfoObject to blueprint as EditorApplySpline() blueprint function as an argument for this type

Expose ULandscapeLayerInfoObject to blueprint as EditorApplySpline() blueprint function as an argument for this type. Some testing might be required to be sure it's not assumed somewhere in the code that it's not exposed or it might give undesired functionality.

1. Create a landscape
2. In blueprint use the EditorApplySpline() blueprint function on the landscape and try providing the last parameter of type ULandscapeLayerInfoObject.