refactor: Transport trait and worker transport, and streamable http client with those new features. (#167)

* refactor: a transport trait and streamable http client

* test: test with js streamable http server

* refactor: separate sse stream connection

* fix(test): streamable http client test with js

* fix(test): wait longer time for js server startup

examples/rig-integration/src/config/mcp.rs

@@ -61,7 +61,7 @@ impl McpServerTransportConfig {
     pub async fn start(&self) -> anyhow::Result<RunningService<RoleClient, ()>> {
         let client = match self {
             McpServerTransportConfig::Sse { url } => {
-                let transport = rmcp::transport::SseTransport::start(url).await?;
+                let transport = rmcp::transport::SseClientTransport::start(url.to_string()).await?;
                 ().serve(transport).await?
             }
             McpServerTransportConfig::Stdio {