p521: add Wycheproof test vectors (#957) #105

Job	Run time
build (1.65.0, thumbv7em-none-eabi)	5m 10s
build (1.65.0, wasm32-unknown-unknown)	3m 27s
build (stable, thumbv7em-none-eabi)	13s
cross (armv7-unknown-linux-gnueabihf, 1.65.0)	8m 3s
build (stable, wasm32-unknown-unknown)	18s
cross (armv7-unknown-linux-gnueabihf, stable)	2m 30s
cross (aarch64-unknown-linux-gnu, 1.65.0)	4m 36s
doc	25s
cross (aarch64-unknown-linux-gnu, stable)	1m 14s
test (i686-unknown-linux-gnu, 1.65.0, sudo apt update && sudo apt install gcc-multilib)	5m 19s
cross (powerpc-unknown-linux-gnu, 1.65.0)	8m 27s
test (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	2m 14s
cross (powerpc-unknown-linux-gnu, stable)	1m 15s
test (x86_64-unknown-linux-gnu, 1.65.0)	8m 22s
test (x86_64-unknown-linux-gnu, stable)	1m 39s
	53m 12s

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