Expose commit (aka private bytes) metric for a function app through MDM

GB-sec usage for a consumption function app is calculated based on how long a function runs for and how much memory was consumed by the sandbox during that time. Specifically, commit / private bytes. This memory usage is limited to 1.5GB per instance.

Ideally, the commit for the process would be captured as a metric and exposed through MDM. This would allow customers to gain an understanding of their memory usage and to create alerts. The latter capability is particularly useful when you consider that the runtime will start throwing OutOfMemoryExceptions once these limits are hit. These exceptions are hard to handle gracefully and some customers would prefer to be notified through these alerts so they can take action in their code/config to reduce the memory footprint of their function app.

By making this metric available through MDM, it would be browsable from the Monitor->Metrics UX in the azure portal.