Split migrations folder (#21549)

There are too many files in `models/migrations` folder so that I split
them into sub folders.

models/migrations/v1_17/v215.go

@@ -0,0 +1,25 @@
+// Copyright 2022 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 v1_17 // nolint
+
+import (
+	"code.gitea.io/gitea/models/pull"
+	"code.gitea.io/gitea/modules/timeutil"
+
+	"xorm.io/xorm"
+)
+
+func AddReviewViewedFiles(x *xorm.Engine) error {
+	type ReviewState struct {
+		ID           int64                       `xorm:"pk autoincr"`
+		UserID       int64                       `xorm:"NOT NULL UNIQUE(pull_commit_user)"`
+		PullID       int64                       `xorm:"NOT NULL INDEX UNIQUE(pull_commit_user) DEFAULT 0"`
+		CommitSHA    string                      `xorm:"NOT NULL VARCHAR(40) UNIQUE(pull_commit_user)"`
+		UpdatedFiles map[string]pull.ViewedState `xorm:"NOT NULL LONGTEXT JSON"`
+		UpdatedUnix  timeutil.TimeStamp          `xorm:"updated"`
+	}
+
+	return x.Sync2(new(ReviewState))
+}