Refactor the error handler

[superstar54]

This PR refactors the error handlers in three ways:
Engine

1. pass task as args, and engine as kwargs
2. return msg to report
3. update the task in the engine

PythonJob
One can attach error_handler to the PythonJob task directly.

Store error handler
Save the module and name if the error handler is globally defined, otherwise, use pickle.

Example

For example, in the decorator's argument:

from aiida_workgraph import WorkGraph, task

def handle_negative_sum(task) -> str:
    """Handle the failure code 410 of the `add`.
    Simply make the inputs positive by taking the absolute value.
    """
    # modify task inputs
    task.set({"x": abs(task.inputs["x"].value),
              "y": abs(task.inputs["y"].value)})
    
    msg = "Run error handler: handle_negative_sum."
    return msg


@task.pythonjob(outputs=[{"name": "sum"}],
                error_handlers=[{"handler": handle_negative_sum,
                                "exit_codes": [410],
                                "max_retries": 5}])
def add(x, y):
    sum = x + y
    if sum < 0:
        exit_code = {"status": 410, "message": "Sum is negative"}
        return {"sum": sum, "exit_code": exit_code}
    return {"sum": sum}

wg = WorkGraph()
wg.add_task(add, name="add1", x=1, y=-2)
wg.submit(wait=True)
print("Task finished OK? ", wg.tasks["add1"].process.is_finished_ok)
print("Exit code: ", wg.tasks["add1"].process.exit_code)
print("Exit Message: ", wg.tasks["add1"].process.exit_message)

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 89.74359% with 12 lines in your changes missing coverage. Please review.

Project coverage is 80.47%. Comparing base (5937b88) to head (9135e05).
Report is 69 commits behind head on main.

Files with missing lines	Patch %	Lines
aiida_workgraph/widget/src/widget/__init__.py	0.00%	4 Missing ⚠️
aiida_workgraph/engine/workgraph.py	89.28%	3 Missing ⚠️
aiida_workgraph/calculations/python.py	0.00%	2 Missing ⚠️
aiida_workgraph/task.py	94.73%	1 Missing ⚠️
aiida_workgraph/utils/__init__.py	92.30%	1 Missing ⚠️
aiida_workgraph/workgraph.py	93.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #302      +/-   ##
==========================================
+ Coverage   75.75%   80.47%   +4.72%     
==========================================
  Files          70       66       -4     
  Lines        4615     5040     +425     
==========================================
+ Hits         3496     4056     +560     
+ Misses       1119      984     -135     

Flag	Coverage Δ
python-3.11	80.39% <89.74%> (+4.73%)	⬆️
python-3.12	80.39% <89.74%> (?)
python-3.9	80.43% <89.74%> (+4.69%)	⬆️

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