Return the (face, i, j) coordinates for the leaf cell corresponding to
this cell id. Since cells are represented by the Hilbert curve position
at the center of the cell, the returned (i,j) for non-leaf cells will be
a leaf cell adjacent to the cell center. If "orientation" is non-nullptr,
also return the Hilbert curve orientation for the current cell.
Return the (face, i, j) coordinates for the leaf cell corresponding to this cell id. Since cells are represented by the Hilbert curve position at the center of the cell, the returned (i,j) for non-leaf cells will be a leaf cell adjacent to the cell center. If "orientation" is non-nullptr, also return the Hilbert curve orientation for the current cell.