Refactor OneLake integration and enhance error handling

- Removed the IsTokenExpired method from OneLakeCredentials as it was unused.
- Added error handling in OneLakeCatalogSet for loading entries to ensure is_loaded state is managed correctly.
- Introduced EnsureLoaded method in OneLakeCatalogSet to centralize loading logic.
- Created new onelake_http_util.cpp for managing HTTP utility functions and environment variable settings for Azure credentials.
- Implemented EnsureHttpBearerSecret to set up Azure client credentials for HTTP requests.
- Enhanced OneLakeSchemaEntry with EnsureTablesLoaded to ensure tables are loaded when needed.
- Improved OneLakeTableEntry to handle Delta format checks and binding logic for table scans.
- Added DiscoverTablesFromStorage function to scan and register tables from OneLake storage.
- Updated OneLakeTableSet to utilize the new storage discovery logic and improved table metadata handling.
- Enhanced error reporting for table discovery and API interactions.