Implement different types of label when migrating Azure DevOps PRs

Overview

This is a follow up issue based on this comment we may need different types of labels and colours per each PR.

Tasks

• Update docs if needed (workflow, runbooks, README, migration metrics, etc.)

Acceptance Criteria

• Existing UTs pass locally
• 100% code coverage on new code

@gitlab-org/professional-services-automation/tools/migration