Create a community metrics dashboard

### Description

Beam has a rich community metrics [dashboard](http://35.193.202.176/d/code_velocity/code-velocity?orgId=1) ([discussion](https://lists.apache.org/thread/0mqo7jfz0ooc1bzvggvw6h0gdlmbd1kl)). Would it help to have something similar?

Review the linked Beam community metrics dashboard and the discussion thread first. Clarify which community metrics Lucene should provide and what a comparable dashboard would include; done requires an agreed scope and implementation plan before coding can begin.

Written by the indexing model from the issue text.