[refactor] replace int with httpStatusCodes (#15282)

* replace "200" (int) with "http.StatusOK" (const)

* ctx.Error & ctx.HTML

* ctx.JSON Part1

* ctx.JSON Part2

* ctx.JSON Part3

routers/org/home.go

@@ -5,6 +5,7 @@
 package org
 
 import (
+	"net/http"
 	"strings"
 
 	"code.gitea.io/gitea/models"
@@ -106,7 +107,7 @@ func Home(ctx *context.Context) {
 	if ctx.User != nil {
 		isMember, err := org.IsOrgMember(ctx.User.ID)
 		if err != nil {
-			ctx.Error(500, "IsOrgMember")
+			ctx.Error(http.StatusInternalServerError, "IsOrgMember")
 			return
 		}
 		opts.PublicOnly = !isMember && !ctx.User.IsAdmin
@@ -137,5 +138,5 @@ func Home(ctx *context.Context) {
 	pager.SetDefaultParams(ctx)
 	ctx.Data["Page"] = pager
 
-	ctx.HTML(200, tplOrgHome)
+	ctx.HTML(http.StatusOK, tplOrgHome)
 }