Patch Release: Refactor OAuth models to structs, extend OAuthUser, and update Vapor

[vamsii777]

This pull request introduces several improvements to the OAuth implementation:

Key Changes:

• Refactored OAuth models to use structs: Enhanced model efficiency and value semantics by transitioning OAuth models from classes to structs.
• Extended OAuthUser struct: Expanded OAuthUser struct functionality to accommodate additional capabilities.
• Refactored OAuthClient and OAuthResourceServer models: Optimized model structure for improved performance and maintainability.
• Upgraded Vapor package to version 4.91.1: Ensured compatibility with the latest Vapor features and bug fixes.

Benefits:

• Improved performance and memory usage: Struct-based models offer potential performance gains and more efficient memory management.
• Enhanced code readability and maintainability: The refactored code adheres to best practices and promotes better understanding.
• Access to latest Vapor features: The updated Vapor package provides access to bug fixes, enhancements, and potential new functionalities.