CloudKMS keys signs data using an specific signature algorithm, in RSA keys,
this can be PKCS#1 RSA or RSA-PSS, if the later is used, x509.CreateCertificate
will fail unless the template SignatureCertificate is properly set.
On contrast, AWSKMS RSA keys, are just RSA keys, and can sign with PKCS#1 or
RSA-PSS schemes, so right now the way to enforce one or the other is to used
templates.
This change makes easier the configuration of cloudCAS as it does
not require to configure the root or intermediate certificate
in the ca.json. CloudCAS will get the root certificate using
the configured certificateAuthority.
