Introduce set_custom_verify_callback and set_async_custom_verify_callback #647

Job	Run time
rustfmt	8s
clippy	1m 33s
Cross build from macOS to Linux (x86_64-unknown-linux-gnu)	2m 50s
Cross build from macOS to Linux (FIPS) (x86_64-unknown-linux-gnu)	6m 50s
Test features	3m 7s
Test (stable)	2m 16s
Test FIPS integration	2m 44s
Test (macos-x86_64)	3m 24s
Test (arm-android)	2m 7s
Test (arm64-android)	2m 6s
Test (i686-android)	2m 19s
Test (x86_64-android)	2m 22s
Test (aarch64-ios)	4m 7s
Test (aarch64-ios-sim)	4m 57s
Test (x86_64-ios)	2m 44s
Test (i686-linux)	3m 21s
Test (arm-linux)	2m 14s
Test (aarch64-linux)	2m 2s
Test (x86_64-musl)	2m 1s
Test (x86_64-mingw)	2m 0s
Test (i686-msvc)	5m 26s
Test (x86_64-msvc)	5m 21s
	1h 5m 59s

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