feat: compile bee to pdl

[starpit]

This also improves error handling in the rust code.

Very primitive support at the moment. No tool calling (yet).

pdl compile beeai input.json -o output.pdl

Where, for now, input.json is generated by hand from a bee program using this monkey patch:

def dry_run(inputs):
    class DryRunAnswer:
        def __init__(self):
            import jsonpickle
            self.final_answer = jsonpickle.encode({"inputs": inputs, "workflow": workflow}, make_refs=False)
    class DryRunResult:
        result = DryRunAnswer()
    class DryRun:
        def on(self,a,b):
            return self
        async def _run_tasks(self):
            return DryRunResult()
        def __await__(self):
            return self._run_tasks().__await__()
    class DryRunContext:
        @staticmethod
        def enter():
            return DryRun()
    return DryRunContext.enter()
workflow.run = dry_run

and with patches to beeai_framework python code to preserve some lexical state that is hidden in a closure. the following does so by adding a meta field to capture the locals() of add_agent()

To workflows/workflow.py:

    def add_step(self, step_name: K, runnable: WorkflowHandler[T, K], meta: dict) -> "Workflow[T, K]":
...
        self.steps[step_name] = WorkflowStepDefinition[T, K](handler=runnable, meta=meta)

To workflows.types.py

class WorkflowStepDefinition(BaseModel, Generic[T, K]):
    meta: dict # add this
    handler: WorkflowHandler[T, K]

To workflows/agent.py add_agent()

        meta = locals()
        del meta["self"]
...
        self.workflow.add_step(name or f"Agent{''.join(random.choice(string.ascii_letters) for _ in range(4))}", step, meta)