feat: zarf file

[blancharda]

Description

Occasionally, it may be useful to transport the identity-config image via zarf package. This PR Adds a simple zarf.yaml and corresponding UDS task for building it.

This will enable custom builds of this repository image to be more easily incorporated in UDS deployments, particularly in situations where the custom image may not be available at bundle create time.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Other (security config, docs update, etc)

[mjnagel]

No issues overall with this - seems useful for custom plugin builders. Could you document the new task in the readme + add a small note or two under docs/CUSTOMIZE.md to explain the zarf package piece?