message: Add custom properties argument to useTrackMetric
diff: import { useEffect, useRef } from "react";
  -import { dateNow } from "@microsoft/applicationinsights-core-js";
  +import { dateNow, ICustomProperties } from "@microsoft/applicationinsights-core-js";
  import ReactPlugin from "./ReactPlugin";
  interface ITrackedData {
  @@ -24,7 +24,8 @@ function getEngagementTimeSeconds(trackedData: ITrackedData) {
  const useComponentTracking = (
  reactPlugin: ReactPlugin,
  - componentName: string
  + componentName: string,
  + customProperties?: ICustomProperties
  ) => {
  const tracking = useRef<ITrackedData>({
  hookTimestamp: dateNow(),
  @@ -76,7 +77,7 @@ const useComponentTracking = (
  sampleCount: 1
  };
  - const additionalProperties = { "Component Name": componentName };
  + const additionalProperties = { "Component Name": componentName, ...customProperties };
  reactPlugin.trackMetric(metricData, additionalProperties);
  };
  }, []);
  