feat: restructure part3 fix examples #4313

Job	Run time
check	18s
check no_std	20s
clippy	49s
check serde	22s
check no_std kzg-rs	29s
check std	22s
test stable --no-default-features	31s
docs	45s
test stable	32s
fmt	6s
test stable --all-features	33s
TyposCheck	5s
test beta --no-default-features	45s
test beta	46s
test beta --all-features	46s
test nightly --no-default-features	35s
test nightly	40s
test nightly --all-features	44s
	9m 28s

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