refactor: Refactor authentication handling and update role assignment

[Pavan1-Microsoft]

Purpose

This pull request introduces several key changes focused on improving authentication flexibility and simplifying API route security. The main updates include adding utility functions for extracting user authentication details, providing a sample user for development, and removing enforced authentication dependencies from multiple API routers. Additionally, there are infrastructure enhancements related to Azure role assignments.

Authentication & Authorization Improvements:

• Added get_authenticated_user_details and get_tenantid utility functions in src/api/auth/auth_utils.py to extract user details and tenant ID from request headers, supporting both Easy Auth and a local development fallback.
• Introduced a sample_user dictionary in src/api/auth/sample_user.py to allow the app to function without authentication in development environments.
• Removed the get_current_user dependency from all API endpoints in src/api/modules/embeddings/router.py, src/api/modules/ingestion/router.py, src/api/modules/pipelines/router.py, and src/api/modules/processing/router.py, making endpoints accessible without enforced authentication. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22]

Infrastructure & Azure Role Assignments:

• Added a new Azure role assignment resource searchContribRole in infra/modules/roles.bicep to grant the backend service principal contributor access to the search service.
• Commented out the AI agent setup step in azure.yaml to prevent failures during deployment when the agent is not required. [1] [2]

These changes collectively improve the developer experience, simplify local development, and enhance infrastructure role management.

Does this introduce a breaking change?

• Yes
• No

Golden Path Validation

• I have tested the primary workflows (the "golden path") to ensure they function correctly without errors.

Deployment Validation

• I have validated the deployment process successfully and all services are running as expected with this change.