Remove wp.Volume

[quagla]

With wp.Volume

Total simulation time: 180.79 s
Total steps per second: 45,312
Total realtime factor: 90.62 x
Total time per step: 22069.03 ns
Total converged worlds: 8192 / 8192

New implementation:

Total simulation time: 71.40 s
Total steps per second: 114,737
Total realtime factor: 229.47 x
Total time per step: 8715.59 ns
Total converged worlds: 8192 / 8192

Note that SDF collisions are not parallelized over the initial points yet (WIP #665)

[adenzler-nvidia]

not sure how this passed CI, but for me test_sdf_collision complains about missing volume_ids. Did I do a bad merge or is this change incomplete?