Add Transporter for wasm js target (#42)

* added js target specific roundtrip

* roundtrip_js dial parameter fix

http/roundtrip.go

@@ -0,0 +1,10 @@
+// TINYGO: The following is copied and modified from Go 1.21.4 official implementation.
+
+//go:build !js
+
+package http
+
+// RoundTrip implements a RoundTripper over HTTP.
+func (t *Transport) RoundTrip(req *Request) (*Response, error) {
+	return roundTrip(req)
+}