Potential compatibility issue of PKCS#12 format

[sunmy2019]

PKCS#12 format required by openssl 1.1.1 and openssl 3.0 (PKCS12_parse) is different. openssl/openssl#6698

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Format 1: openssl 1.1 required:
CN = Leaf
CN = Root
CN = CA #2
CN = CA #1

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Format 2: openssl 3.0 required:
CN = Leaf
CN = CA #1
CN = CA #2
CN = Root

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This causes compatibility issues in rust-native-rls. sfackler/rust-native-tls#281

rust-native-tls officially supports Format 2, when used with openssl 1.1.
And in practice, it also supports Format 1, when used with openssl 3.0.

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Luckily, in our use cases, we only have Leaf and Root. Format 1 and Format 2 are the same. Our users are less likely to be affected.

This is a kind note for users with compatibility issues for PKCS#12.