Migrate reactions when migrating repository from github (#9599)

* Migrate reactions when migrating repository from github

* fix missed sleep

* fix tests

* update reactions when external user binding

* Fix test

* fix tests

* change the copy head

* fix test

* fix migrator add/delete reaction

models/migrations/v123.go

@@ -0,0 +1,18 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package migrations
+
+import (
+	"xorm.io/xorm"
+)
+
+func addReactionOriginals(x *xorm.Engine) error {
+	type Reaction struct {
+		OriginalAuthorID int64 `xorm:"INDEX NOT NULL DEFAULT(0)"`
+		OriginalAuthor   string
+	}
+
+	return x.Sync2(new(Reaction))
+}