CLI: Add database metrics flow scaffolding

Problem

General problem: described in the epic.

We want to make a first step towards generating database metrics with internal events CLI.

Desired Outcome

Set up the architecture that will be used for creating database metrics.

Potential Solution

Create a new flow that creates database metrics. Use existing MetricDefiner class to generate a barebones yml metric file.

Documentation Update Needed

• Yes
• No

How to verify

Further actions needed