Expose `secp256k1` and `keccak256` in the SDK #3358

Job	Run time
build-fuzz	1m 54s
check-git-rev-deps	16s
build-and-test (ubuntu-latest, x86_64-unknown-linux-gnu)	4m 11s
cargo-deny (advisories)	4m 18s
build-and-test (ubuntu-latest, aarch64-unknown-linux-gnu, true)	3m 24s
cargo-deny (bans licenses sources)	5m 28s
docs	3m 57s
build-and-test (macos-latest, x86_64-apple-darwin)	19m 17s
fmt	9s
build-and-test (macos-latest, aarch64-apple-darwin)	16m 27s
build-and-test (windows-latest, x86_64-pc-windows-msvc)	18m 6s
rust-analyzer-compat	11m 33s
publish-dry-run	0s
complete	2s
	1h 29m 2s

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