[APIView] Implement Azure App Service Easy Auth to replace Azure AD authentication through custom JWT validation

APIView has been flagged for not using MISE (Microsoft Identity Service Engine) for Azure AD token validation. Our current custom JWT validation approach is non-compliant with Microsoft identity standards.

## 🎯 Solution
Migrate from custom JWT validation to Azure App Service Easy Auth, which uses MISE under the hood and ensures full compliance with Microsoft identity requirements.

## 🔍 Background
- **Current State**: Custom JWT token validation in application code
- **Compliance Issue**: Not using MISE for token validation
- **Constraint**: Cannot implement MISE directly in application
- **Solution**: Azure App Service Easy Auth (platform-level MISE integration)

Start by locating APIView's current custom JWT validation and the Azure App Service configuration that controls authentication. Confirm how Easy Auth can replace application-level validation without direct MISE integration; done means Azure AD requests use Easy Auth and the custom validation path is no longer required.

Written by the indexing model from the issue text.