feat(socketio/state): global state implementation backed by a state::TypeMap

[Totodore]

This PR adds global state management as well as a State extractor to get the state in any handlers.

Note : Before merging this PR, it is necessary to use dynamics handler for the on_disconnect function. Otherwise it wont be possible to use the state in these handlers.

Currently it is not possible to use the references in extractors because of the following problem :
In the ConnectHandler implementation below for any function with arguments that implements FromConnectParts and are specified by values. To add a lifetime to extractors we could add a lifetime on the trait FromConnectParts. The problem is that the provided lifetime should be the one declared with the for<'a> corresponding to the function and its scope is rather limited.

impl<A, F, $($ty,)*> ConnectHandler<A, (private::Sync, $($ty,)*)> for F
        where
            F: for<'a> FnOnce($($ty,)*) + Send + Sync + Clone + 'static,  // The lifetime 'a should be propagated to the `FromConnectParts` 
            A: Adapter,                                                   // ---------------------------------------
            $( $ty: FromConnectParts<'a, A> + Send, )*                    // <----- here
        {
            fn call(
                &self,
                s: Arc<Socket<A>>,
                auth: Option<String>,
                state: &Arc<dyn std::any::Any + Send + Sync>)
            {
                $(
                    let $ty = match $ty::from_connect_parts(&s, &auth,  state) {
                        Ok(v) => v,
                        Err(_e) => {
                            #[cfg(feature = "tracing")]
                            tracing::error!("Error while extracting data: {}", _e);
                            return;
                        },
                    };
                )*

                (self.clone())($($ty,)*);
            }
        }

Because of this issue the state will be static so that State extractors only contains &'static references and don't need lifetime propagation.

• Fixes State Management #178

[tausifcreates]

💯