add staticFS supports

[zxysilent]

add staticFS

Checklist

• [x ] Dependencies installed
• [x ] No typos
• Searched existing issues and docs

Expected behaviour

Actual behaviour

Steps to reproduce

Working code to debug

package main

import (
	"embed"
	 "net/http"
	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
)

//go:embed static
var static embed.FS
func main() {
	engine := echo.New()
	engine.Static("/static", "static")
	// use embed
	engine.StaticFS("/staticfs",http.FS(static))
	// or
	engine.StaticFS("/staticfs",static)
	engine.Start("8080")
}

Version/commit

[aldas]

Static middleware has now support for Filesystem. This was added with #1797 and will be release in v4.3.

	e.Use(middleware.StaticWithConfig(middleware.StaticConfig{
		Root:       ".",
		Filesystem: http.FS(os.DirFS("../_fixture")),
	}))