Using OpenSSL 3.0.7, packaged by OpenVPN Windows installer, causes
EasyRSA command 'build-ca' to fail, because it does not have an input
password to re-open the private key, which is required to generate
the CA certificate.

Provide the user specified CA passphrase as input password for build-ca.

Signed-off-by: Richard T Bonhomme <tincantech@protonmail.com>

If 'easyrsa' is being run by the unit-test then allow the default method
for 'build-ca' to be exercised.

The default 'easyrsa' method is to use temp-files, generated by EasyRSA,
to pass the CA passphrase, provided by the user, to the SSL command.

The normal 'unit-test' method to use a passphrase is to configure EasyRSA
ommand line options '--passin' and '--passout'.

The change made here is to simulate user-interaction and to supply a
default passphrase, as a user, to the SSL command.
To NOT use EasyRSA command line options to set any passphrase.
ONLY when being run by the unit-test.

Signed-off-by: Richard T Bonhomme <tincantech@protonmail.com>

Signed-off-by: Richard T Bonhomme <tincantech@protonmail.com>

Also, prototype easyrsa_mktemp() errors.

Signed-off-by: Richard T Bonhomme <tincantech@protonmail.com>