Change description

This change adds a new optional option to the Ecto plugin configuration - duration_unit.
It allows the user to override the time unit of the Ecto metrics, allowing to directly pass it through to :telemetry.

What problem does this solve?

Issue number: #139

Example usage

{Plugins.Ecto, [repos: [Shared.Repo], duration_unit: :second]}

Additional details and screenshots

Checklist

• I have added unit tests to cover my changes.
• I have added documentation to cover my changes.
• My changes have passed unit tests and have been tested E2E in an example project.