Add Musig2 module #1124

Job	Run time
Cross (aarch64-unknown-linux-gnu)	1m 12s
Cross (i686-unknown-linux-gnu)	1m 9s
Cross (x86_64-pc-windows-gnu)	2m 9s
Cross (x86_64-unknown-linux-gnu)	1m 8s
Cross (aarch64-unknown-linux-musl)	2m 26s
Cross (arm-unknown-linux-gnueabi)	2m 12s
Cross (arm-unknown-linux-gnueabihf)	2m 14s
Cross (armv7-unknown-linux-gnueabihf)	1m 40s
Cross (powerpc-unknown-linux-gnu)	2m 32s
Cross (powerpc64le-unknown-linux-gnu)	1m 3s
Cross (riscv64gc-unknown-linux-gnu)	1m 48s
Cross (s390x-unknown-linux-gnu)	2m 14s
Cross (x86_64-unknown-linux-musl)	1m 38s
	23m 25s

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