Add Collection of Metrics when Measurements are passed to Events

[JacksonWeber]

• When one or more measurements are passed to manual .trackEvent() calls, we should collect those as individual metrics.
• Added tests to ensure that metrics are created when measurements are passed.

[JacksonWeber]

Closing in favor of the solution in the exporter: https://github.com/Azure/azure-sdk-for-js/pull/29511