Expose consensus critical metrics directly from gpbft

[masih]

This repo provides f3 observe command to dump all messages exchanged as part of F3. One then would need to query them to answer questions like:

• Who is currently participating?
• What percentage of power is participating?

This is fine but not ideal. Because, gpbft already has all of this information along with the cache of all the validated messages. For alerting purposes alone it would be useful not to force operators to run an observer to get these metrics.