Partitioned databases

[smithsz]

Checklist

• [x] Tick to sign-off your agreement to the Developer Certificate of Origin (DCO) 1.1
• [x] Added tests for code changes or test/build only changes
• [x] Updated the change log file (CHANGES.md|CHANGELOG.md) or test/build only changes
• [x] Completed the PR template below:

Description

Add partitioned databases feature.

See partitioned_databases.rst.

Schema & API Changes

New API (non-breaking).

Security and Privacy

No change.

Testing

Includes additional testing.

Monitoring and Logging

No change.

[emlaver]

Given that we have all the other function descriptions/examples under Getting Started, does it make sense to have Partitioned Databases in its own separate doc section?

[smithsz]

@emlaver Moved under the 'Databases' heading...