[AzureWeAppCounters] Trace UserActionable trace message if counter is not supported so it will be easier to troubleshoot

[SergeyKanzhelev]

1. Create an EventSource like this: https://github.com/Microsoft/ApplicationInsights-SDK-Labs/blob/customCounters/AggregateMetrics/AggregateMetrics/AggregateMetricsEventSource.cs Keep Microsoft-ApplicationInsights-Extensibility prefix
2. Define Error-level event marked as UserActionable that will say something like "Counter {0} is not supported by Azure Web App" and pass the counters name
3. Report this error from Module