Connector redesign

[isabellelaususan]

Feature description
Connector redesign based on this document
https://www.notion.so/teamanalog/Connector-Redesign-5a2dd536e3284aa7917ee3a3552124a7

/// Possible transaction statuses returned from [`Client::poll_next_event()`].
pub enum TxStatus<ID> {
    /// Transaction is part of the future queue.
    Validated,
    /// The transaction has been broadcast to other nodes.
    Broadcasted,
    /// Transaction is no longer in a best block.
    NoLongerInBestBlock,
    /// Transaction has been included in block with given hash.
    InBestBlock(ID),
    /// Transaction has been finalized by a finality-gadget, e.g GRANDPA
    InFinalizedBlock(ID),
    /// Something went wrong in the node.
    Error {
        /// Human readable message; what went wrong.
        message: String,
    },
    /// Transaction is invalid (bad nonce, signature etc).
    Invalid {
        /// Human readable message; why was it invalid.
        message: String,
    },
    /// The transaction was dropped.
    Dropped {
        /// Human readable message; why was it dropped.
        message: String,
    },
}

/// Event generated by the `Client`.
pub enum ClientEvent<T: Client> {
    /// Event generated by the Client
    Notify(T::Event),

    /// Informs that the tx status was updated
    TxStatus { id: T::TransactionIdentifier, result: Result<TxStatus<T>, T::Error> },
    
    /// Query Result
    Query { id: T::QueryId, result: Result<T::ViewCallResult, T::Error> },

    /// Close the connection for the given reason.
    Close(T::Error),
}

pub trait Client: Sized {
    // Transactions
    type TransactionIdentifier;
    type Transaction: Encode + Decode;
    
    // View Calls
    type ViewCallIdentifier;
    type ViewCall: Encode + Decode;
    type ViewCallResult: Encode + Decode;

    // Client Events
    type Event;
    type Error: Debug;

    /// Submits a signed transaction
    fn submit(
        &mut self,
        tx: Self::Transaction,
    ) -> Result<Self::TransactionIdentifier, Self::Error>;

    /// Query some read-only data
    fn view_call(
        &mut self,
        query: Self::ViewCall,
    ) -> Result<Self::ViewCallIdentifier, Self::Error>;

    /// Should behave like `Stream::poll()`.
    fn poll_next_event(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<ClientEvent<Self>>;
}

Expected output

• Make connector API Opaque
• Detect availability errors (ex: offline RPC, unsync Client, request timeout, fatal errors, etc)
• Detect protocol errors (ex: eth_call which reverts, out of gas, invalid view call, etc)

Tests instructions

• Unit tests
• Integration tests

References Material

• Technical Specs
• Related docs
• Example code

Additional Information