Bugfix: Support returning json serializable objects from an orchestrator function

[ZainRizvi]

Currently you can send an arbitrary json-serializable to a sub orchestrator, but that sub orchestrator cannot return the same object.

This because the input param's serializer falls back to using a generic custom obj serializer, but the orchestrator return value doesn't get the same special treatment.

Fixes in this PR

• Pass in the same serializer to both invocations of json.dumps(). This let's custom objects get correctly returned.
• Fix the type hinting on OrchestratorState.to_json() since it can set the value of the dictionary to self._output and self._error, both of which are typehinted as being of Any type

I suspect (but haven't verified) that this also fixes a similar bug that prevents the custom_status from being set to a custom json-serializable object

Missing from this PR

Tests. Sorry for not adding them in but I didn't feel like learning the new test framework for this PR. I tested this manually, and if you guys want unit tests for this then I'm hoping it's trivial for you folks to add.

More context

Without this fix, returning a custom JSON-serializable method results in this error:

[2024-03-09T17:44:24.704Z] Executed 'Functions.some_orchestrator' (Failed, Id=605291c9-282c-48eb-986e-d28307099dc6, Duration=228ms)
[2024-03-09T17:44:24.708Z] System.Private.CoreLib: Exception while executing function: Functions.some_orchestrator. System.Private.CoreLib: Orchestrator function 'some_orchestrator' failed: One or more errors occurred. (Result: Failure
Exception: TypeError: Object of type MyCustomObjectis not JSON serializable
Stack:   File "C:\Program Files\Microsoft\Azure Functions Core Tools\workers\python\3.10\WINDOWS\X64\azure_functions_worker\dispatcher.py", line 495, in _handle__invocation_request      
    call_result = await self._loop.run_in_executor(
  File "C:\Python310\lib\concurrent\futures\thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
  File "C:\Program Files\Microsoft\Azure Functions Core Tools\workers\python\3.10\WINDOWS\X64\azure_functions_worker\dispatcher.py", line 768, in _run_sync_func
    return ExtensionManager.get_sync_invocation_wrapper(context,
  File "C:\Program Files\Microsoft\Azure Functions Core Tools\workers\python\3.10\WINDOWS\X64\azure_functions_worker\extension.py", line 215, in _raw_invocation_wrapper
    result = function(**args)
  File "C:\Users\...\fnOrchestrator\.venv\lib\site-packages\azure\durable_functions\orchestrator.py", line 69, in handle
    return Orchestrator(fn).handle(DurableOrchestrationContext.from_json(context_body))
  File "C:\Users\...\fnOrchestrator\.venv\lib\site-packages\azure\durable_functions\orchestrator.py", line 47, in handle
    return self.task_orchestration_executor.execute(context, context.histories, self.fn)
  File "C:\Users\...\fnOrchestrator\.venv\lib\site-packages\azure\durable_functions\models\TaskOrchestrationExecutor.py", line 104, in execute
    return self.get_orchestrator_state_str()
  File "C:\Users\...\fnOrchestrator\.venv\lib\site-packages\azure\durable_functions\models\TaskOrchestrationExecutor.py", line 296, in get_orchestrator_state_str
    return state.to_json_string()
  File "C:\Users\...\fnOrchestrator\.venv\lib\site-packages\azure\durable_functions\models\OrchestratorState.py", line 121, in to_json_string
    return json.dumps(json_dict)
  File "C:\Python310\lib\json\__init__.py", line 231, in dumps
    return _default_encoder.encode(obj)
  File "C:\Python310\lib\json\encoder.py", line 199, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "C:\Python310\lib\json\encoder.py", line 257, in iterencode
    return _iterencode(o, 0)
  File "C:\Python310\lib\json\encoder.py", line 179, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '
).

[cgillum]

The change LGTM! I'll wait for @davidmrdavid to take a quick look to confirm before merging.

[davidmrdavid]

Good catch, thank you for your contribution @ZainRizvi

[ZainRizvi]

My pleasure @davidmrdavid. Any idea when this fix might get released?

[davidmrdavid]

@ZainRizvi - hopefully within the next month or so. We're a bit spread thin at the moment, but there's a few more small changes planned for the SDK that I'd like to include before the next release. I'll track your request to release this asap in my ToDo list though

[mych4nge]

@davidmrdavid Wouldn't it make sense to make small intermediate bugfix-release containing this fix only?
Or is there any other way to get this change in my app?