add **encoding** argument in netCDF4 backend

[wqshen]

add encoding argument in netCDF4 backend to support reading NetCDF file with non-ASCII path or filename.

The behavior is consistent with upstream netCDF4 library, default path encoding is set to sys.getdefaultfileencoding() .

• Closes Support an encoding parameter when reading netCDF files with xarray #10357 Cannot read a nc file that contains the diacritic mark tilde (á) in the path #8531

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[dcherian]

Nice, can you add a test here please?

xarray/xarray/tests/test_backends.py

Line 2037 in d589df1

class TestNetCDF4Data(NetCDF4Base):

It can simply roundtrip a simple dataset to a file with a filename that doesn't work today.

[kmuehlbauer]

How is this handled in the light of this comment #9282 (comment) by @dcherian?

[dcherian]

Hah! Probably good to use filename_encoding since we'll probably to support writing files with such file names.