Reorganize workflow examples and improve code structure

[forrestIsRunning]

Changes:

1. Reorganized workflow example files to better reflect their purposes
   • Moved main() to main.go
   • Renamed original main.go to simple_workflow_example.go
2. Improved function naming to follow Go conventions
3. Added two different workflow examples:
   • A simple workflow without explicit task management
   • A complex workflow with multiple tasks and proper workflow management

This PR improves code organization and makes the examples more clear for users to understand the different ways to use the SDK.