feat: implement TGraph-writing #3670

Job	Run time
build (windows-latest, 3.8)	8m 19s
build (windows-latest, 3.9)	8m 24s
vanilla-build (windows-latest, 3.11)	5m 18s
build (windows-latest, 3.10)	8m 33s
vanilla-build (ubuntu-latest, 3.11)	3m 29s
build (windows-latest, 3.11)	7m 50s
vanilla-build (macos-latest, 3.11)	6m 28s
build (windows-latest, 3.12)	7m 29s
build (macos-latest, 3.8)	8m 47s
build (macos-latest, 3.9)	6m 39s
build (macos-latest, 3.10)	6m 38s
build (macos-latest, 3.11)	6m 7s
build (macos-latest, 3.12)	6m 33s
build (ubuntu-latest, 3.8)	20m 59s
build (ubuntu-latest, 3.9)	9m 10s
build (ubuntu-latest, 3.10)	16m 28s
build (ubuntu-latest, 3.11)	25m 22s
build (ubuntu-latest, 3.12)	17m 27s
	3h 0m 0s

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