Removing Field.to_write and FieldSet.to_write methods #751

Job	Run time
mypy	3m 35s
py3.13 \| macos \| integration tests	7m 31s
py3.13 \| macos \| unit tests	4m 30s
py3.13 \| ubuntu \| unit tests	5m 32s
py3.13 \| ubuntu \| integration tests	7m 29s
py3.13 \| windows \| unit tests	7m 15s
py3.10 \| ubuntu \| unit tests	5m 29s
py3.13 \| windows \| integration tests	7m 19s
py3.11 \| ubuntu \| unit tests	5m 29s
py3.10 \| ubuntu \| integration tests	7m 29s
py3.12 \| ubuntu \| unit tests	5m 52s
merge-test-artifacts	1s
	1h 7m 31s

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