refactor middleware generator (#159)

* rebase upstream

* rebase

* trim no need line

* trim no need line

* trim no need line

* update doc

* remove update

* remove no need

* remove no need

* goctl add jwt support

* goctl add jwt support

* goctl add jwt support

* goctl support import

* goctl support import

* support return ()

* revert

* refactor and rename folder to group

* remove no need

* add anonymous annotation

* optimized

* rename

* rename

* update test

* api add middleware support: usage:

@server(
    middleware: M1, M2
)

* api add middleware support: usage:

@server(
    middleware: M1, M2
)

* simple logic

* optimized

* optimized generator formatted code

* optimized generator formatted code

* add more test

* refactor middleware generator

* revert test

* revert test

* revert test

* revert test

* revert test

Co-authored-by: kingxt <dream4kingxt@163.com>

tools/goctl/api/gogen/genmiddleware.go

@@ -0,0 +1,59 @@
+package gogen
+
+import (
+	"bytes"
+	"strings"
+	"text/template"
+
+	"github.com/tal-tech/go-zero/tools/goctl/api/util"
+)
+
+var middlewareImplementCode = `
+package middleware
+
+import "net/http"
+
+type {{.name}} struct {
+}
+
+func New{{.name}}() *{{.name}} {	
+	return &{{.name}}{}
+}
+
+func (m *{{.name}})Handle(next http.HandlerFunc) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		// TODO generate middleware implement function, delete after code implementation
+
+		// Passthrough to next handler if need 
+		next(w, r)
+	}	
+}
+`
+
+func genMiddleware(dir string, middlewares []string) error {
+	for _, item := range middlewares {
+		filename := strings.TrimSuffix(strings.ToLower(item), "middleware") + "middleware" + ".go"
+		fp, created, err := util.MaybeCreateFile(dir, middlewareDir, filename)
+		if err != nil {
+			return err
+		}
+		if !created {
+			return nil
+		}
+		defer fp.Close()
+
+		name := strings.TrimSuffix(item, "Middleware") + "Middleware"
+		t := template.Must(template.New("contextTemplate").Parse(middlewareImplementCode))
+		buffer := new(bytes.Buffer)
+		err = t.Execute(buffer, map[string]string{
+			"name": strings.Title(name),
+		})
+		if err != nil {
+			return nil
+		}
+		formatCode := formatCode(buffer.String())
+		_, err = fp.WriteString(formatCode)
+		return err
+	}
+	return nil
+}