Configuration option to select model

Add instance-level Configuration option to select either the default LLM (Vertex / Anthropic) by Duo feature

• the ability to configure offered (GA) Duo features to the offered OS models
• for each feature, a drop down menu of the available models
• user is prompted to input necessary fields (authentification, endpoint, versioning, resource allocation, etc)
• presentation of clear documentation on each model, use case, and how each model fits to a use case based on validation
• upon selection of a model for a feature, validated prompts will be auto configured specific to that model and feature.
• Propose top-level group for this feature

See also

See also Configuration in Self-Hosted Model Deployment Blueprint (!148599 - merged) and https://gitlab.com/gitlab-org/gitlab/-/blob/a1879fad78ab5ea76f61d172184274a52283f8c1/doc/architecture/blueprints/custom_models/index.md

graph LR
    a1 --> c1
    a2 --> b1
    b1 --> c1
    b3 --> b1
    b4 --> b1
    c1 --> c2
    c2 --> c3
    c3 --> d1
    d1 --> d2

    subgraph "User"
      a1[IDE Request]
      a2[Web / CLI Request]
    end

    subgraph "Self-Managed GitLab"
      b1[GitLab Duo Feature] <--> b2[Model & Feature-specific<br/>Prompt Retrieval]
      b3[GitLab Duo Feature<br/>Configuration]
      b4[LLM Serving Config]
    end

    subgraph "Self-Hosted AI Gateway"
      c1[Inbound API interface]
      c2[Model routing]
      c3[Model API interface]
    end

    subgraph "Self-Hosted LLM"
      d1[LoadBalancer]
      d2[GPU-based backend]
    end

Dropdown

There will be a dropdown for each Duo Feature. The following options will be available:

• Default Model (Vertex or Anthropic)
• Mistral 7B
• Mixtral 8x7B
• Feature Inactive

Definition of Done

• Backend storage for choices
• REST API for AI Gateway to access the settings
• Frontend
• Add to menu