Add instrumentation for VSA stage page views

Problem

In order to discover best practices for VSA we want to understand what are the most frequently used customized streams.

We need to answer these questions:

1. How many stage are active and how many are stale?
2. What stage most frequently used by customers?
3. What start_event most frequently used?
4. What stop_event most frequently used?

Proposal

1. Add instrumentation to collect # of stage views.
2. Count of unique and total views.
3. Event data should include stream_name, stage_name, start_event, stop_event, account id, timestamp, by tier
4. Both SaaS and SM