Certificate output providers

[AMEST]

To simplify the integration of the client for issuing certificates (as well as for automating the issuance of certificates), it would be convenient to choose where and in what way the certificate will be sent.
For example, upon completion of the client's work, he could send ready-made certificates to the gitlab repository, where ci-cd rolled out this certificate across servers, or he himself would put these certificates on sftp to the right place on the server.

Road map:

1. Abstraction of certificate output
2. Implementation for saving to local file system (default)
3. Implementation for saving to the repository in gitlab
4. Implementation for saving via sftp