[BUG] The file descriptor for cuFile (GDS) is not closed after use

[gigony]

Describe the bug

If a CuFileDriver instance is created by the file descriptor (fd), the file descriptor needs to be closed manually.
However, if the CuFileDriver instance is created by cucim.clara.filesystem.open() method, its file descriptor needs to be closed automatically when the reference count is zero.

Steps/Code to reproduce bug

from cucim.clara.filesystem import CuFileDriver
import cucim.clara.filesystem as fs
import os, cupy as cp, torch

# Create a CuPy array with size 10 (in bytes)
cp_arr = cp.ones(10, dtype=cp.uint8)
# Create a PyTorch array with size 10 (in bytes)
cuda0 = torch.device('cuda:0')
torch_arr = torch.ones(10, dtype=torch.uint8, device=cuda0)

# Using CuFileDriver
# (Opening a file with O_DIRECT flag is required for GDS)
fno = os.open("input.raw", os.O_RDONLY | os.O_DIRECT)
with CuFileDriver(fno) as fd:
  # Read 8 bytes starting from file offset 0 into buffer offset 2
  read_count = fd.pread(cp_arr, 8, 0, 2)
  # Read 10 bytes starting from file offset 3
  read_count = fd.pread(torch_arr, 10, 3)
os.close(fno)

# Another way of opening file with cuFile
with fs.open("output.raw", "w") as fd:
  # Write 10 bytes from cp_array to file starting from offset 5
  write_count = fd.pwrite(cp_arr, 10, 5)
  #############################################
  # <=== file descriptor created by fs.open() is not closed when exiting the scope
  #############################################

Expected behavior
It should close the file descriptor.

Environment details (please complete the following information):

• Environment location: Bare-metal
• Method of cuCIM install: pip, from source