Function encode_metrics 

fn encode_metrics(
    table_writer: &mut MultiTableData,
    metric: &Metric,
    metadata: &MetricMetadata,
    resource_attrs: Option<&Vec<KeyValue>>,
    scope_attrs: Option<&Vec<KeyValue>>,
    metric_ctx: &OtlpMetricCtx,
    outcome: &mut MetricsIngestOutcome,
    exemplars: &mut Vec<RowExemplars>,
) -> Result<()>