refactor: Add BerkeleyDatabaseVersion() function

Summary:
This is a backport of core#16710 [1/2]
https://github.com/bitcoin/bitcoin/pull/16710/commits/de5e91c3034f320f84ee0308a3c31659635d136a

This is backported out of order. In the original PR, it should have touched db.{h|c}, but the code was moved to bdb.{h|c} in D8615. The original PR includes only db.h in rpcconsole.cpp, and bdb.h should have been added additionaly in D8615 (both includes will be needed for subsequent backports (e.g. core#20202).

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D10209