[dbsql] [ffapi] DB Stats and Metrics

[onelapahead]

Redo of #205

We nabled build info metrics and have ffapi tests to ensure the metrics endpoint works as expected.

DB metrics are in two forms:

1. stats collector wraps Stats() from *sql.DB with basic gauges around conn settings and pool usage
   instrumentation of all operations and transactions
2. Similar to ffresty, there's then a global func for clients to enable DB metrics, ensuring all initialized databases in a process are metered by the collector and instrumentation.