Add namespace for custom metrics

[hectorhdzg]

Fixes #609

[MSNev]

Is this something we should be adding to the web code as well?
We only have these
export class DataPoint {

/**
 * Name of the metric.
 */
public name: string;

/**
 * Metric type. Single measurement or the aggregated value.
 */
public kind: DataPointType = DataPointType.Measurement;

/**
 * Single value for measurement. Sum of individual measurements for the aggregation.
 */
public value: number;

/**
 * Metric weight of the aggregated metric. Should not be set for a measurement.
 */
public count: number;

/**
 * Minimum value of the aggregated metric. Should not be set for a measurement.
 */
public min: number;

/**
 * Maximum value of the aggregated metric. Should not be set for a measurement.
 */
public max: number;

/**
 * Standard deviation of the aggregated metric. Should not be set for a measurement.
 */
public stdDev: number;

}

[hectorhdzg]

Yes, you should, "ns" is the actual field we put in the envelope, namespace is the property name of the class we expose in the API

[MSNev]

OK, will raise an issue on AI-JS