feat(http/h2c): h2c test server with a Dockerfile

- Implemented a basic HTTP/2 server that responds with "ok" to requests.
- Updated dev.compose.yml to include a service for it

cmd/h2c_test_server/main.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"log"
+	"net/http"
+
+	"golang.org/x/net/http2"
+	"golang.org/x/net/http2/h2c"
+)
+
+func main() {
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte("ok"))
+	})
+
+	server := &http.Server{
+		Addr:    ":80",
+		Handler: h2c.NewHandler(handler, &http2.Server{}),
+	}
+
+	log.Println("H2C server listening on :8080")
+	if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+		log.Fatalf("ListenAndServe: %v", err)
+	}
+}