Refactor ReasoningAgent for direct Azure AI Search integration

Refactored ReasoningAgentTemplate to use direct AzureAIAgentClient and integrate Azure AI Search via a new ReasoningSearch helper. Improved initialization, search augmentation, and resource management. Updated reasoning_search.py for better logging, error handling, and framework-agnostic usage. Added detailed docstrings and clarified configuration and usage patterns.

Author: Fr4nc3