Fix pc.LayerComposition insert methods to work like Array.splice works
Fix pc.LayerComposition insert methods to work like Array.splice works

playcanvas/engine,aidinabedi/playcanvas-engine,playcanvas/engine,sereepap2029/playcanvas,sereepap2029/playcanvas,sereepap2029/playcanvas,MicroWorldwide/PlayCanvas,MicroWorldwide/PlayCanvas,aidinabedi/playcanvas-engine