feat: enhance shutdown function to accept context for improved control

[kanywst]

Overview

Enhanced the shutdown functionality to accept a context parameter, allowing for more control over timeout settings and other context-specific configurations during the shutdown process.

Changes

• Added a new ShutdownWithContext(ctx context.Context) function that accepts a user-provided context
• Refactored the existing Shutdown() function to use ShutdownWithContext() with context.Background() for backward compatibility
• The new function uses the provided context to shut down the server gracefully

Testing

• Added unit tests to verify the new functionality works as expected

Related Issue

#172