Reorganizing OAuth Flow

[rodrigobr-msft]

This pull request refactors the OAuth flow handling and related authentication logic in the Microsoft Agents Hosting Core library. The changes modernize the flow management, introduce new abstractions, and improve code clarity and maintainability. The most significant updates include replacing the legacy SignInState mechanism with a new FlowState-based system, updating imports and type definitions.

OAuth Flow Refactor and Abstractions

• Introduced new classes and enums: FlowState, FlowStateTag, FlowErrorTag, and FlowResponse for managing OAuth flows, replacing the previous SignInState-based approach. (libraries/microsoft-agents-hosting-core/microsoft/agents/hosting/core/oauth/flow_state.py, [1] [2] [3]
• Added FlowStorageClient and refactored OAuth flow handling to use FlowResponse and FlowState objects for more robust state management. (libraries/microsoft-agents-hosting-core/microsoft/agents/hosting/core/oauth/__init__.py, libraries/microsoft-agents-hosting-core/microsoft/agents/hosting/core/oauth/init.pyR1-R16)

Agent Application Logic Refactor

• Refactored turn and activity handling in agent_application.py to use the new flow state and response logic, including new helper methods for handling flow responses and intercepting authentication turns. (libraries/microsoft-agents-hosting-core/microsoft/agents/hosting/core/app/agent_application.py, [1] [2] [3]
• Removed legacy sign-in state logic and replaced it with flow state checks and response handling. (libraries/microsoft-agents-hosting-core/microsoft/agents/hosting/core/app/agent_application.py, libraries/microsoft-agents-hosting-core/microsoft/agents/hosting/core/app/agent_application.pyL610-R703)

Codebase and Import Cleanup

• Updated and reorganized imports across multiple __init__.py files to reflect the new abstractions and remove unused or obsolete references. (libraries/microsoft-agents-hosting-core/microsoft/agents/hosting/core/__init__.py, [1] [2] [3] [4] [5] [6] [7] [8] [9]

Minor Improvements

• Added a __bool__ method to TokenResponse for clearer truthiness checks. (libraries/microsoft-agents-activity/microsoft/agents/activity/token_response.py, libraries/microsoft-agents-activity/microsoft/agents/activity/token_response.pyR26-R28)