add workflow failure reason

[LawyZheng]

[!IMPORTANT] Add failure_reason to workflow_runs and update related logic to capture and store failure reasons during workflow execution.

• Database Changes:
  • Add failure_reason column to workflow_runs table in Alembic migration 2024_11_15_0251-1909715536dc_add_failure_reason_column_to_workflow_.py.
  • Update WorkflowRunModel in models.py to include failure_reason.
• Functionality:
  • Modify update_workflow_run() in client.py to accept failure_reason.
  • Update execute_safe() in block.py to set failure_reason on exceptions.
  • Enhance execute_workflow() in service.py to log failure_reason when blocks fail.
• Models and Conversions:
  • Update convert_to_workflow_run() in utils.py to include failure_reason.
  • Add failure_reason to WorkflowRun in workflow.py.
• Miscellaneous:
  • Update various block execution methods in block.py to handle failure_reason.
  • Adjust logging and error handling to incorporate failure_reason in service.py.

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