What area(s) will this request affect?

Theme

What type of change do you want to see?

New feature

Overview

Introduce a theme duplicate command in the cli, so developers can duplicate a theme in the library.

Motivation

Pushing an entire new theme via cli takes considerably longer than duplicating a pre existing theme - especially in cases where the merchant has lots of assets.

In my workflow, I never overwrite the live theme directly. Instead, when deploying, I create a new theme and allow the merchant to review it before making the decision to publish.

With the duplicate command, I could simply duplicate the live theme and push any changes to it - in that case only the files that have changed will be overwritten.