ParticleFile refactor and re-integration into v4-dev #1259

Job	Run time
mypy	0s
py3.12 \| ubuntu \| unit tests	6m 3s
py3.11 \| ubuntu \| unit tests	5m 58s
py${{ matrix.python-version }} \| ${{ matrix.os }} \| integration tests	0s
merge-test-artifacts	-1s
	12m 0s

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