[FEATURE] Automatic checking of existing valid SSL certificates

**Is your feature request related to a problem? Please describe.**
When running the playbook against a host that already has a previous deployment with an SSL certificate issued from the role, the `certbot` asks for interaction to choose whether it should keep the existing certificate or renew it; this causes the role to hang as it does not expect any interaction.

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What do you want to do?
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1: Keep the existing certificate for now
2: Renew and replace the certificate (may be subject to CA fee limits)
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```

**Describe your desired solution**
An automated check for existing, valid, and matching certificates for the host.

**Describe the alternatives you have considered**
For now, it is possible to skip certificate generation by setting the `ssl` variable of the role to an empty string.