Citizen/animgraph: rework input-based lean layers
The upper body lean component now works much better, and is nicely staggered with the additive pelvis position component. A copy of the system, with different settings, is now applied while crouching, which improves settling back to idle. The upper body bit is still a bit hacky due to the lack of model-space additive support, but this works OK enough for now. The entire system is composited in *before* the "center delta" system, so it can't stomp any non-default idle poses anymore.