Allow UrlJsonRpcProvider to receive connectionInfo

[Nebulis]

The InfuraProvider class hierarchy is as follows:

InfuraProvider <= UrlJsonRpcProvider <= StaticJsonRpcProvider <= JsonRpcProvider <= and so on :)

InfuraProvider expects 2 arguments, a network and an API key. JsonRpcProvider expects a connection object or a URL. When we create an InfuraProvider, the connection information is automatically created through UrlJsonRpcProvider constructor. However, there is currently no way to customise the connection information.

My suggestion is to add a 3rd argument to UrlJsonRpcProvider constructor, so that we can be able to customise the connection information. Something like:

constructor(network?: Networkish, apiKey?: any, connectionInfo?:ConnectionInfo = {}) {
        logger.checkAbstract(new.target, UrlJsonRpcProvider);

        // Normalize the Network and API Key
        network = getStatic<(network: Networkish) => Network>(new.target, "getNetwork")(network);
        apiKey = getStatic<(apiKey: string) => string>(new.target, "getApiKey")(apiKey);

        const connection = { ...getStatic<getUrlFunc>(new.target, "getUrl")(network, apiKey), ...conectionInfo};

        super(connection, network);

        if (typeof(apiKey) === "string") {
            defineReadOnly(this, "apiKey", apiKey);
        } else if (apiKey != null) {
            Object.keys(apiKey).forEach((key) => {
                defineReadOnly<any, any>(this, key, apiKey[key]);
            });
        }
    }

This would benefit any provider that inherits UrlJsonRpcProvider such as Infura, Alchemy, etc.

Any thoughts ?