k256+primeorder: add `batch_normalize_generic` #151

Job	Run time
build (1.65.0, thumbv7em-none-eabi)	5m 29s
build (1.65.0, wasm32-unknown-unknown)	3m 42s
cross (armv7-unknown-linux-gnueabihf, 1.65.0)	4m 45s
cross (armv7-unknown-linux-gnueabihf, stable)	1m 13s
build (stable, thumbv7em-none-eabi)	35s
cross (aarch64-unknown-linux-gnu, 1.65.0)	8m 43s
cross (aarch64-unknown-linux-gnu, stable)	1m 9s
build (stable, wasm32-unknown-unknown)	16s
doc	16s
cross (powerpc-unknown-linux-gnu, 1.65.0)	4m 49s
test (i686-unknown-linux-gnu, 1.65.0, sudo apt update && sudo apt install gcc-multilib)	4m 57s
cross (powerpc-unknown-linux-gnu, stable)	1m 10s
test (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	1m 30s
test (x86_64-unknown-linux-gnu, 1.65.0)	8m 8s
test (x86_64-unknown-linux-gnu, stable)	1m 52s
	48m 34s

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