Move Sinsemilla primitive impl into `sinsemilla` crate #4053

Job	Run time
Bitrot check	1m 29s
Code coverage	3m 43s
Build target wasm32-unknown-unknown	1m 49s
Test on ubuntu-latest	1m 33s
Build target wasm32-wasi	1m 40s
Test on windows-latest	1m 31s
Test on i686-unknown-linux-gnu	13m 48s
Book tests	1m 21s
Test on macOS-latest	1m 34s
Test on i686-unknown-linux-gnu with beta features	12m 57s
Test on ubuntu-latest with beta features	1m 34s
Test on i686-unknown-linux-gnu with nightly features	15m 1s
Test on windows-latest with beta features	1m 31s
Intra-doc links	1m 25s
Test on macOS-latest with beta features	1m 31s
Rustfmt	13s
Test on ubuntu-latest with nightly features	1m 34s
Test on windows-latest with nightly features	1m 32s
Test on macOS-latest with nightly features	1m 33s
	1h 7m 19s

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