open-webui support namespaces

[kerthcet]

What would you like to be added:

Following the https://github.com/InftyAI/llmaz/blob/main/docs/open-webui.md, we can only serve the models in one namespace, we should extend this to kubernetes namespace mechanism, for example, integrate with the workspace in openwebui.

Why is this needed:

Completion requirements:

The admin should have access to all the models within one website.

This enhancement requires the following artifacts:

• Design doc
• API change
• Docs update

The artifacts should be linked in subsequent comments.

[kerthcet]

/help