Split migrations folder (#21549)

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

models/migrations/v1_16/v206.go

@@ -0,0 +1,29 @@
+// 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_16 //nolint
+
+import (
+	"fmt"
+
+	"xorm.io/xorm"
+)
+
+func AddAuthorizeColForTeamUnit(x *xorm.Engine) error {
+	type TeamUnit struct {
+		ID         int64 `xorm:"pk autoincr"`
+		OrgID      int64 `xorm:"INDEX"`
+		TeamID     int64 `xorm:"UNIQUE(s)"`
+		Type       int   `xorm:"UNIQUE(s)"`
+		AccessMode int
+	}
+
+	if err := x.Sync2(new(TeamUnit)); err != nil {
+		return fmt.Errorf("sync2: %w", err)
+	}
+
+	// migrate old permission
+	_, err := x.Exec("UPDATE team_unit SET access_mode = (SELECT authorize FROM team WHERE team.id = team_unit.team_id)")
+	return err
+}