chore: move type def to where it belongs (#1391) #4240

Job	Run time
docs	1m 1s
cfg-check	28s
clippy	40s
check no_std	20s
doctest	1m 7s
feature-checks	3m 16s
fmt	12s
wasm-wasi	1m 8s
wasm-unknown	49s
test ubuntu-latest stable --no-default-features	1m 27s
test ubuntu-latest stable	1m 26s
test ubuntu-latest stable --all-features	2m 26s
test ubuntu-latest nightly --no-default-features	1m 21s
test ubuntu-latest nightly	1m 6s
test ubuntu-latest nightly --all-features	2m 6s
test ubuntu-latest 1.79 --no-default-features	31s
test ubuntu-latest 1.79	39s
test windows-latest stable --no-default-features	5m 30s
test windows-latest stable	6m 12s
test windows-latest stable --all-features	6m 56s
test windows-latest nightly --no-default-features	4m 2s
test windows-latest nightly	3m 45s
test windows-latest nightly --all-features	5m 29s
test windows-latest 1.79 --no-default-features	2m 45s
test windows-latest 1.79	3m 16s
	57m 58s

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