Add handles graph to metrics

How: Add handles graph to metrics

Why: There is no way to view the metrics of 'handles'

For Who: For customers who are getting "High Resource Utilization" mails every now and then :)

Impact: -

Additional context:

You, as a customer, or partner, are questioned about 'handles', but Inriver has NO explanation about it, and you also don't get any view into these 'handles'.