Looks for the main object renderer task in the frame graph.
By default, this is the object/geometry renderer task with isMainObjectRenderer set to true.
If no such task, we return the last object/geometry renderer task that has an object list with meshes (or null if none found).
Parameters
frameGraph: FrameGraph
The frame graph to search in
Returns Nullable<FrameGraphObjectRendererTask>
The main object renderer of the frame graph, or null if not found
Looks for the main object renderer task in the frame graph. By default, this is the object/geometry renderer task with isMainObjectRenderer set to true. If no such task, we return the last object/geometry renderer task that has an object list with meshes (or null if none found).