feat: add new router and ping route to main application

- Remove the import statement for "github.com/gin-gonic/gin" in main.go
- Add a new file called router.go in the router directory
- Create a new function called New() in router.go that returns a *gin.Engine
- Add a GET route for "/ping" in the New() function in router.go

Signed-off-by: appleboy <appleboy.tw@gmail.com>

router/router.go

@@ -0,0 +1,11 @@
+package router
+
+import "github.com/gin-gonic/gin"
+
+func New() *gin.Engine {
+	r := gin.Default()
+	r.GET("/ping", func(c *gin.Context) {
+		c.String(200, "pong")
+	})
+	return r
+}