Removing Field.to_write and FieldSet.to_write methods #757

Job	Run time
mypy	3m 43s
py3.13 \| macos \| integration tests	15m 14s
py3.13 \| macos \| unit tests	7m 55s
py3.13 \| ubuntu \| integration tests	20m 34s
py3.13 \| ubuntu \| unit tests	9m 49s
py3.13 \| windows \| integration tests	24m 25s
py3.13 \| windows \| unit tests	13m 58s
py3.10 \| ubuntu \| integration tests	14m 0s
py3.10 \| ubuntu \| unit tests	10m 46s
py3.11 \| ubuntu \| unit tests	10m 24s
py3.12 \| ubuntu \| unit tests	10m 14s
merge-test-artifacts	4s
	2h 21m 6s

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