feat: add observability labels

[reneca]

Following tests on Grafana Cloud, metrics are not perfect regarding labels.
From service semantic conventions we should have service.instance.id, service.namespace, service.name.
This triplet MUST be globally unique, so this change add these missing labels to have a job and instance on Grafana Cloud metrics.

[oschijns]

I cannot test it yet.
Overall looks fine, but the pipeline failed.
(Looks like an unrelated issue.)

[reneca]

For Windows we could include:

#[cfg(target_os = "windows")]
if let Ok(output) = Command::new("reg")
    .args(["query", r"HKLM\SOFTWARE\Microsoft\Cryptography", "/v", "MachineGuid"])
    .output()
    && output.status.success()
    && let Ok(output_str) = String::from_utf8(output.stdout)
{
    for line in output_str.lines() {
        if line.contains("MachineGuid")
            && let Some(value) = line.split_whitespace().last()
            && let Ok(machine_uuid) = Uuid::parse_str(value.trim())
        {
            return machine_uuid.to_string();
        }
    }
}

But the compilation is a mess, so don't need to include it yet.