Swagger info corrections (#9441)

* use numbers and not http.Status___ enum

* fix test

* add many missing swagger responses

* code format

* Deletion Sould return 204 ...

* error handling improvements

* if special error type ... then add it to swagger too

* one smal nit

* invalidTopicsError is []string

* valid swagger specification 2.0
 - if you add responses swagger can tell you if you do it right 👍

* use ctx.InternalServerError

* Revert "use numbers and not http.Status___ enum"

This reverts commit b1ff386e24.

* use http.Status* enum everywhere

routers/api/v1/misc/version.go

@@ -5,6 +5,8 @@
 package misc
 
 import (
+	"net/http"
+
 	"code.gitea.io/gitea/modules/context"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/structs"
@@ -20,5 +22,5 @@ func Version(ctx *context.APIContext) {
 	// responses:
 	//   "200":
 	//     "$ref": "#/responses/ServerVersion"
-	ctx.JSON(200, &structs.ServerVersion{Version: setting.AppVer})
+	ctx.JSON(http.StatusOK, &structs.ServerVersion{Version: setting.AppVer})
 }