feat: make StateHandle's Id public

[discord9]

make StateHandle's Id public, so one can link state with subgraph by using something like BTreeMap<SubgraphId, BTreeSet<StateId>>

[MingweiSamuel]

Whats your use case? Also would prefer to have it as a method instead

[discord9]

Whats your use case? Also would prefer to have it as a method instead

Then I should make it a method then, how about state_id() for naming?
For example, I want to allow related subgraph to run when the state related to it fulfilled certain condition(i.e. certain amount of time have passed), I'm using scheduled api heavily in my usecase, but I feel hydro lang could alos be benefited from having a way to manage state with id?

// Suppose this state have some timed task 
// that needed to be done later when certain condition is fulfilled
// call `Hydroflow::add_state::<Rc<RefCell<State>>>` and also register state in manager with it's id
let state = manager.add_state::<State>();
let state_id = state.state_id();
let subgraph_id = df.add_subgraph(/* code that use this state*/);
// This manager register state to subgraph by id, and schedule related subgraph to run when state's condition is fulfilled
manager.register_state_to_subgraph*(state_id, subgraph_id);

[MingweiSamuel]

Would #1054 work for you?

[discord9]

Would #1054 work for you?

Yes, it can cover my use case, thanks