pybelnsor with configurable simulation stages

[chenzhaiyu]

Current behavior:

### convert base meshes to ply
Running loop for <function _convert_mesh at 0x7fbfcbd19d30> with 760 calls on 40 subprocess workers
### clean mesh
Running loop for <function _clean_mesh at 0x7fbfc7943700> with 760 calls on 40 subprocess workers
### scale and translate mesh
Running loop for <function _normalize_mesh at 0x7fbfc80309d0> with 760 calls on 40 subprocess workers
### sample with Blensor
Running loop for <function mp_worker at 0x7fbf51b749d0> with 760 calls on 40 subprocess workers
### convert pcd to pts
Running loop for <function _pcd_files_to_pts at 0x7fbfc7943430> with 760 calls on 40 subprocess workers
### make query points, calculate signed distances
### get query points
Running loop for <function _get_and_save_query_pts at 0x7fbfc7943ee0> with 760 calls on 40 subprocess workers

Expected behavior:
Allowing execution of specific stages, e.g., without query points.