feat: add Azure AI Search integration for OpenAI models

[roomote]

This PR implements Azure AI Search integration for OpenAI models from Azure Foundry, allowing users to leverage internal documentation and knowledge bases that AI models are not trained on.

Summary

This feature adds the ability to use Azure AI Search as a data source when using OpenAI models through Azure Foundry. When enabled, it adds a data_sources field to the API request that allows the model to reference and use documents from the configured search index.

Changes

• Added Azure AI Search configuration fields to the provider settings schema
• Updated OpenAICompatible UI component with Azure AI Search configuration options including:
  • Enable/disable toggle
  • Search endpoint and index configuration
  • Authentication settings
  • Embedding model configuration
  • Query type selection
  • Search parameters (top N documents, strictness)
• Modified openai.ts provider to construct and include the data_sources field when Azure AI Search is enabled
• Added comprehensive tests for all Azure AI Search functionality
• Added translation keys for all new UI elements

Testing

• All existing tests pass
• Added new test suite specifically for Azure AI Search functionality
• TypeScript compilation successful for both backend and frontend

Screenshots

The UI now includes an "Enable Azure AI Search" checkbox in the OpenAI Compatible settings. When enabled, users can configure:

• Azure AI Search endpoint
• Index name
• API keys for both search and embedding models
• Query type (simple, semantic, vector, hybrid options)
• Number of documents to retrieve
• Search strictness level

Notes

• This feature only works when using Azure OpenAI (when "Use Azure" is checked)
• The implementation follows the Azure AI Foundry API specification for data sources
• All sensitive information (API keys) are stored securely using VSCode's secret storage

Fixes #6282

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Important

Adds Azure AI Search integration to OpenAI models, enabling internal document usage via data_sources field with comprehensive configuration and testing.

• Behavior:
  • Adds Azure AI Search integration for OpenAI models, enabling use of internal documents via data_sources field.
  • Supports configuration of search endpoint, index, authentication, embedding model, query type, and search parameters.
  • Only works with Azure OpenAI.
• Configuration:
  • Adds Azure AI Search fields to openAiSchema in provider-settings.ts.
  • Updates OpenAICompatible component with Azure AI Search options.
• Backend:
  • Modifies OpenAiHandler in openai.ts to include data_sources when Azure AI Search is enabled.
  • Implements buildAzureAiSearchDataSources() to construct data source configuration.
• Testing:
  • Adds tests in openai.spec.ts to verify Azure AI Search functionality, including cases with/without embedding configuration and different query types.
• UI:
  • Updates UI in OpenAICompatible.tsx to include Azure AI Search settings.
  • Adds translation keys for new UI elements in settings.json.

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