Build SSL Certificate Management Automation into Graylog GUI

## What?

Installing an SSL certificate on the Graylog web interface should be an option in the Configuration section of the GUI. Users should be able to do basic certificate management:

1. Generate a CSR for a provider & install the returned certificate OR
2. Configure Let's Encrypt to automate the management of the certificate OR
3. Install a public / private key pair along with the intermediate certificate (This would apply to installing a Cloudflare origin cert for example)

## Why?

The current process for installing and maintaining an SSL certificate on the web interface is too complex. With certificates now expiring every 90 days, this creates a ton of unnecessary work for the end user as well as requires the end user to learn the nuances of using OpenSSL and adding certificates to the Java vault.

End users should be spending their time getting value of out of Graylog, not administering Linux.

## Your Environment

* Graylog Version:
* OpenSearch Version:
* MongoDB Version:
* Operating System:
* Browser version: