use same certificate generation settings as helm template functions

[viccuad]

As we are using genCA and genSigneCert helm template functions to bootstrap the initial certificates, we need to use the same settings as helm to re-generate the certificates during the rotation process.

Helm uses sprig to expose the certificate generation template functions.
We will need to use the same settings as sprig, see: https://github.com/Masterminds/sprig/blob/master/crypto.go

[viccuad]

@fabriziosestito could you expand a bit on this issue?