Function build_on_demand_acme 

fn build_on_demand_acme(
    ctx: &mut TlsBuildContext,
    server: &ServerConfiguration,
    port: u16,
    sni_hostname: Option<String>,
    challenge_type: ChallengeType,
    dns_provider: Option<Arc<dyn DnsProvider + Send + Sync>>,
    crypto_provider: Arc<CryptoProvider>,
) -> Result<()>

Builds an on-demand ACME configuration.

On-demand ACME defers certificate issuance until a client connects and requests a hostname that does not yet have a certificate. This is typically used for wildcard or dynamic hostnames.