Journaling system

[justinchuby]

Use a context manager to create new journals which can be serialized as json. It can be replayed and recreate the graph.

@track_changes
def name(self, value):
    ...

will create Action("name", <traceback>) in the object meta, also serialized into metadata_props

class Action:
    id: int
    type: str
    field: Literal["INIT", "UPDATE", "ADD_NODE", ...]
    value: Any
    call_stack: str
    timestamp: int

Ref:
https://github.com/pytorch/pytorch/blob/main/torch/fx/passes/graph_transform_observer.py