HITL - Decouple agents from users.

[0mdc]

Motivation and Context

This changeset decouples the concept of 'user' and 'agent' in the rearrange_v2 application to the application to be used by either human users or AIs.

How Has This Been Tested

Tested locally.

Types of changes

• [Development]

Checklist

• [x] My code follows the code style of this project.
• [x] I have updated the documentation if required.
• [x] I have read the CONTRIBUTING document.
• [x] I have completed my CLA (see CONTRIBUTING)
• [x] I have added tests to cover my changes if required.