This PR adds support for generating a self-signed CA and then using that CA to generate TLS certificates.
A new tool `duplicati-configure` / `Duplicati.CommandLine.ConfigureTool.exe` is added to manage the certificates. The tool saves the configuration in the database and is meant to run with elevated privileges for the initial CA installation.
The option `--configure-https` can be added to server/trayicon, and if the process has permissions, this will automatically install the CA certificate.
If a CA is configured, the server will automatically issue, renew and use a TLS certificate.
With this setup, the TLS is opt-in, but once the flow is well tested, we can switch it to opt-out.