[Feature]: Allow showing aliases in `/v1/models`

[Manouchehri]

The Feature

For this config:

litellm_settings:
  fallbacks: [{"gemini-1.0-pro": ["gemini-1.0-pro-vertex"]}] # fallback to Vertex if call fails num_retries

router_settings:
  model_group_alias: {"gemini-pro": "gemini-1.0-pro"}

model_list:
  - model_name: gemini-1.0-pro-vertex
    litellm_params:
      model: vertex_ai/gemini-1.0-pro
      vertex_project: epic-project
      vertex_location: us-east4
      hide_from_model_list: True

  - model_name: gemini-1.0-pro
    litellm_params:
      model: gemini/gemini-1.0-pro
      hide_from_model_list: True

I would want this output from /v1/models:

{
  "data": [
    {
      "id": "gemini-pro",
      "object": "model",
      "created": 1677610602,
      "owned_by": "openai"
    }
  ],
  "object": "list"
}

Motivation, pitch

Same motivation as #2835, making it cleaner for our developers on what model name they should use in their projects.

Twitter / LinkedIn details

https://twitter.com/DaveManouchehri

[MchLrnX]

This would be really good to have.

[krrishdholakia]

This is now supported @Manouchehri