Expose hmac_sha256/512 functions #757

Job	Run time
Cross build from macOS to Linux (FIPS) (x86_64-unknown-linux-gnu)	2m 11s
Cross build from macOS to Linux (x86_64-unknown-linux-gnu)	1m 47s
rustfmt	7s
clippy	1m 56s
Test features	6m 6s
Test (stable)	2m 1s
Test FIPS integration	2m 52s
Test (arm-android)	2m 13s
Test (arm64-android)	2m 0s
Test (i686-android)	2m 26s
Test (x86_64-android)	1m 55s
Test (aarch64-ios)	2m 20s
Test (aarch64-ios-sim)	2m 13s
Test (x86_64-ios)	2m 19s
Test (i686-linux)	3m 5s
Test (arm-linux)	2m 53s
Test (aarch64-linux)	2m 23s
Test (arm64-macos)	2m 38s
Test (x86_64-macos)	2m 23s
Test (x86_64-mingw)	4m 52s
Test (i686-msvc)	7m 46s
Test (x86_64-msvc)	8m 0s
	1h 6m 26s

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