abstract provider and transport for ScrollAuthEngineProvider

[greged93]

This would allow for any transport to be used (ws, ipc, http), instead of currently being constrained to http.

          I wonder if it's possible to make this generic over the `Provider` and `Transport` (the `Network` should be hard coded to `Scroll`). This would allow us to use different providers/transport protocols to interact with the node (ws / HTTP). I think it should be possible something like this but I haven't got it working yet:

/// An authenticated [`alloy_provider::Provider`] to the [`super::ScrollEngineApi`].
#[derive(Debug, Clone, Deref)]
pub struct ScrollAuthEngineApiProvider<ProviderT, TransportT> {
    #[deref]
    provider: ProviderT,
    _marker: std::marker::PhantomData<TransportT>,
}

impl<ProviderT, TransportT> ScrollAuthEngineApiProvider<ProviderT, TransportT>
where
    ProviderT: Provider<TransportT, Scroll>,
    TransportT: Transport + Clone,
{
    /// Returns a new [`ScrollAuthEngineApiProvider`], authenticated for interfacing with the Engine
    /// API server at the provided URL using the passed JWT secret.
    pub fn new(jwt_secret: JwtSecret, url: Url) -> Self {
        let auth_layer = AuthLayer::new(jwt_secret);
        let hyper_client = hyper_util::client::legacy::Client::builder(TokioExecutor::new())
            .build_http::<Full<Bytes>>();

        let service = tower::ServiceBuilder::new().layer(auth_layer).service(hyper_client);
        let transport = HyperClient::<Full<Bytes>, _>::with_service(service);

        let is_url_local = guess_local_url(&url);
        let http = Http::with_client(transport, url);
        let client = RpcClient::new(http, is_url_local);
        let provider = ProviderBuilder::new().network::<Scroll>().on_client(client);

        Self { provider, _marker: Default::default() }
    }
}

          I suggest you timebox this to an hour to see if you can get it working. If not then we will merge as is.

Originally posted by @frisitano in #147 (comment)