split `PackedModule` into reader and writer #26347

Job	Run time
ubuntu-20.04 (batch: allowed_failures)	8m 7s
ubuntu-20.04 (batch: 0_3)	29m 47s
ubuntu-20.04 (batch: 1_3)	19m 58s
ubuntu-20.04 (batch: 2_3)	19m 17s
macos-12 (batch: allowed_failures)	11m 11s
macos-12 (batch: 0_3)	34m 9s
macos-12 (batch: 1_3)	37m 45s
macos-12 (batch: 2_3)	25m 35s
	3h 5m 49s

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