feat(socket-proxy): implement Docker socket proxy and related configurations

- Updated Dockerfile and Makefile for socket-proxy build.
- Modified go.mod to include necessary dependencies.
- Updated CI workflows for socket-proxy integration.
- Better module isolation
- Code refactor

socket-proxy/cmd/main.go

@@ -0,0 +1,16 @@
+package main
+
+import (
+	"log"
+	"net/http"
+
+	socketproxy "github.com/yusing/go-proxy/socketproxy/pkg"
+)
+
+func main() {
+	if socketproxy.ListenAddr == "" {
+		log.Fatal("Docker socket address is not set")
+	}
+	log.Printf("Docker socket listening on: %s", socketproxy.ListenAddr)
+	http.ListenAndServe(socketproxy.ListenAddr, socketproxy.NewHandler())
+}