Simplify iotype implementation #375

Job	Run time
NIF 2.15 - aarch64-apple-darwin (macos-11 \| default)	34m 5s
NIF 2.15 - aarch64-unknown-linux-gnu (ubuntu-20.04 \| default)	9m 9s
NIF 2.15 - aarch64-unknown-linux-musl (ubuntu-20.04 \| default)	9m 0s
NIF 2.15 - x86_64-apple-darwin (macos-11 \| default)	33m 31s
NIF 2.15 - x86_64-pc-windows-gnu (windows-2022 \| default)	18m 23s
NIF 2.15 - x86_64-pc-windows-gnu (windows-2022 \| legacy_cpu)	20m 9s
NIF 2.15 - x86_64-pc-windows-msvc (windows-2019 \| default)	19m 35s
NIF 2.15 - x86_64-pc-windows-msvc (windows-2019 \| legacy_cpu)	19m 10s
NIF 2.15 - x86_64-unknown-freebsd (ubuntu-22.04 \| default)	9m 11s
NIF 2.15 - x86_64-unknown-freebsd (ubuntu-22.04 \| legacy_cpu)	9m 32s
NIF 2.15 - x86_64-unknown-linux-gnu (ubuntu-20.04 \| default)	8m 17s
NIF 2.15 - x86_64-unknown-linux-gnu (ubuntu-20.04 \| legacy_cpu)	8m 25s
NIF 2.15 - x86_64-unknown-linux-musl (ubuntu-20.04 \| default)	8m 55s
	3h 27m 22s

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