Data loaders should be able to inject tags to the graph

[skrawcz]

Is your feature request related to a problem? Please describe.
I'm a central platform team. I own some data adapters. I want to be able to inject some tags into the graph on the nodes.

Describe the solution you'd like
Data loaders can be used in many contexts. So I think the only way to get some tags is after instantiation, and a function is called.

Something like

@dataclasses.dataclass
class JSONDataLoader(DataLoader):
    path: str

    @classmethod
    def applicable_types(cls) -> Collection[Type]:
        return [dict]

    def load_data(self, type_: Type) -> Tuple[dict, Dict[str, Any]]:
        with open(self.path, "r") as f:
            return json.load(f), get_file_metadata(self.path)

    @classmethod
    def name(cls) -> str:
        return "json"

    def tags(self) -> dict:  # <------------- add something like this
        return {"some_special_tag": self.path, ...}

Describe alternatives you've considered
It's not critical, but something to think about.

Additional context
If one was to build more capabilities using tag metadata, then we'd want this here.