Log Event Hubs related exceptions captured by ProcessErrorAsync

[paulbatum]

This code appears to be silently throwing away errors that come from event processor host.

azure-webjobs-sdk/src/Microsoft.Azure.WebJobs.ServiceBus/EventHubs/EventHubListener.cs

Lines 117 to 121 in 901764c

	public Task ProcessErrorAsync(PartitionContext context, Exception error)
	{
	// TODO: log underlying event hubs error
	return Task.CompletedTask;
	}

We need to wire this code path up to both system logs and application logs.

[paulbatum]

Ideally fix for both functions v1, v2

[pragnagopa]

Will not be porting this fix to V1 as ProcessErrorAsync - helper method where we can log underlying errors is only available in V2 as it depends on Microsoft.Azure.EventHubs.Processor. V1 depends on Microsoft.Azure.ServiceBus which does not have an equivalent of ProcessErrorAsync.