Refactor `filenames` handling in `Field.from_netcdf` #358

Job	Run time
mypy	3m 55s
py3.13 \| macos \| integration tests	6m 34s
py3.13 \| macos \| unit tests	6m 35s
py3.13 \| ubuntu \| integration tests	6m 34s
py3.13 \| ubuntu \| unit tests	6m 33s
py3.13 \| windows \| integration tests	6m 19s
py3.13 \| windows \| unit tests	6m 16s
py3.10 \| ubuntu \| integration tests	6m 32s
py3.10 \| ubuntu \| unit tests	6m 30s
py3.11 \| ubuntu \| unit tests	6m 30s
py3.12 \| ubuntu \| unit tests	6m 31s
merge-test-artifacts	1s
	1h 8m 50s

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