Reorder migrations, skip errors if running migration again (#3160)

* Reorder migrations, skip errors if running migration again

* Rename migration file names to match migration version

* Add note about ingored error

models/migrations/v53.go

@@ -0,0 +1,28 @@
+// Copyright 2017 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 (
+	"fmt"
+
+	"github.com/go-xorm/xorm"
+)
+
+func addReactions(x *xorm.Engine) error {
+	// Reaction see models/issue_reaction.go
+	type Reaction struct {
+		ID          int64  `xorm:"pk autoincr"`
+		Type        string `xorm:"INDEX UNIQUE(s) NOT NULL"`
+		IssueID     int64  `xorm:"INDEX UNIQUE(s) NOT NULL"`
+		CommentID   int64  `xorm:"INDEX UNIQUE(s)"`
+		UserID      int64  `xorm:"INDEX UNIQUE(s) NOT NULL"`
+		CreatedUnix int64  `xorm:"INDEX created"`
+	}
+
+	if err := x.Sync2(new(Reaction)); err != nil {
+		return fmt.Errorf("Sync2: %v", err)
+	}
+	return nil
+}