Add credBlob-extension #404

Job	Run time
build (ubuntu-latest, x86_64-unknown-linux-gnu, true, sudo apt-get update sudo apt-get install -y...	1m 11s
build (ubuntu-latest, x86_64-unknown-linux-gnu, true, sudo apt-get update sudo apt-get install -y...	3m 56s
build (ubuntu-latest, x86_64-unknown-linux-gnu, true, sudo apt-get update sudo apt-get install -y...	1m 17s
build (macos-latest, x86_64-apple-darwin, true, --features crypto_dummy --no-default-features --t...	1m 36s
build (windows-latest, x86_64-pc-windows-gnu, true, --features crypto_dummy --no-default-features...	2m 32s
build (ubuntu-latest, x86_64-unknown-freebsd, false, sudo apt-get update sudo apt-get install -y ...	55s
build (ubuntu-latest, x86_64-unknown-netbsd, false, sudo apt-get update sudo apt-get install -y l...	58s
build (ubuntu-latest, x86_64-linux-android, false, sudo apt-get update sudo apt-get install -y li...	46s
	13m 11s

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