Split migrations folder (#21549)

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

models/migrations/v1_13/v146.go

@@ -0,0 +1,84 @@
+// 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 v1_13 //nolint
+
+import (
+	"code.gitea.io/gitea/modules/timeutil"
+
+	"xorm.io/xorm"
+)
+
+func AddProjectsInfo(x *xorm.Engine) error {
+	// Create new tables
+	type (
+		ProjectType      uint8
+		ProjectBoardType uint8
+	)
+
+	type Project struct {
+		ID          int64  `xorm:"pk autoincr"`
+		Title       string `xorm:"INDEX NOT NULL"`
+		Description string `xorm:"TEXT"`
+		RepoID      int64  `xorm:"INDEX"`
+		CreatorID   int64  `xorm:"NOT NULL"`
+		IsClosed    bool   `xorm:"INDEX"`
+
+		BoardType ProjectBoardType
+		Type      ProjectType
+
+		ClosedDateUnix timeutil.TimeStamp
+		CreatedUnix    timeutil.TimeStamp `xorm:"INDEX created"`
+		UpdatedUnix    timeutil.TimeStamp `xorm:"INDEX updated"`
+	}
+
+	if err := x.Sync2(new(Project)); err != nil {
+		return err
+	}
+
+	type Comment struct {
+		OldProjectID int64
+		ProjectID    int64
+	}
+
+	if err := x.Sync2(new(Comment)); err != nil {
+		return err
+	}
+
+	type Repository struct {
+		ID                int64
+		NumProjects       int `xorm:"NOT NULL DEFAULT 0"`
+		NumClosedProjects int `xorm:"NOT NULL DEFAULT 0"`
+	}
+
+	if err := x.Sync2(new(Repository)); err != nil {
+		return err
+	}
+
+	// ProjectIssue saves relation from issue to a project
+	type ProjectIssue struct {
+		ID             int64 `xorm:"pk autoincr"`
+		IssueID        int64 `xorm:"INDEX"`
+		ProjectID      int64 `xorm:"INDEX"`
+		ProjectBoardID int64 `xorm:"INDEX"`
+	}
+
+	if err := x.Sync2(new(ProjectIssue)); err != nil {
+		return err
+	}
+
+	type ProjectBoard struct {
+		ID      int64 `xorm:"pk autoincr"`
+		Title   string
+		Default bool `xorm:"NOT NULL DEFAULT false"`
+
+		ProjectID int64 `xorm:"INDEX NOT NULL"`
+		CreatorID int64 `xorm:"NOT NULL"`
+
+		CreatedUnix timeutil.TimeStamp `xorm:"INDEX created"`
+		UpdatedUnix timeutil.TimeStamp `xorm:"INDEX updated"`
+	}
+
+	return x.Sync2(new(ProjectBoard))
+}