Add round operator implementation

[GordonYang1]

pytest output:

================================================ test session starts ================================================
platform linux -- Python 3.10.12, pytest-9.0.2, pluggy-1.6.0 -- /home/spack/spack2/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.4.0/python-3.10.12-7k7oi7tgey4aaqibwibyx2uzbhy2pptb/bin/python3.10
cachedir: .pytest_cache
rootdir: /data/shared/yangzhenyu/ntops
configfile: pyproject.toml
collected 8 items                                                                                                   

tests/test_round.py::test_round[shape0-dtype0-cuda-0.001-0.001] PASSED                                        [ 12%]
tests/test_round.py::test_round[shape1-dtype1-cuda-0.01-0.01] PASSED                                          [ 25%]
tests/test_round.py::test_round[shape2-dtype2-cuda-0.001-0.001] PASSED                                        [ 37%]
tests/test_round.py::test_round[shape3-dtype3-cuda-0.01-0.01] PASSED                                          [ 50%]
tests/test_round.py::test_round[shape4-dtype4-cuda-0.001-0.001] PASSED                                        [ 62%]
tests/test_round.py::test_round[shape5-dtype5-cuda-0.01-0.01] PASSED                                          [ 75%]
tests/test_round.py::test_round[shape6-dtype6-cuda-0.001-0.001] PASSED                                        [ 87%]
tests/test_round.py::test_round[shape7-dtype7-cuda-0.01-0.01] PASSED                                          [100%]

================================================= 8 passed in 3.98s =================================================