apps/pkcs12: Do not assume null termination of ASN1_UTF8STRING
apps/pkcs12: Do not assume null termination of ASN1_UTF8STRING

Reviewed-by: Paul Dale <ddec78389666b4f7c9b4d110380c848489a3e4aa@openssl.org>
Reviewed-by: Bernd Edlinger <ac6902843ae77cc0d49b9c8ddec4cbf141db1bb7@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/16433)

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl