Function register_histogram_vec_with_subsystem

pub fn register_histogram_vec_with_subsystem(
    subsystem: &str,
    name: &str,
    description: &str,
    label_names: &[&str],
    buckets: Option<Vec<f64>>,
) -> HistogramVec

Wrapper around Prometheus register_histogram_vec! macro with linera namespace and a subsystem. Results in metrics named linera_<subsystem>_<name>.