Split migrations folder (#21549)

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

models/migrations/v1_14/v164.go

@@ -0,0 +1,38 @@
+// 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_14 //nolint
+
+import (
+	"fmt"
+
+	"xorm.io/xorm"
+)
+
+// OAuth2Grant here is a snapshot of models.OAuth2Grant for this version
+// of the database, as it does not appear to have been added as a part
+// of a previous migration.
+type OAuth2Grant struct {
+	ID            int64  `xorm:"pk autoincr"`
+	UserID        int64  `xorm:"INDEX unique(user_application)"`
+	ApplicationID int64  `xorm:"INDEX unique(user_application)"`
+	Counter       int64  `xorm:"NOT NULL DEFAULT 1"`
+	Scope         string `xorm:"TEXT"`
+	Nonce         string `xorm:"TEXT"`
+	CreatedUnix   int64  `xorm:"created"`
+	UpdatedUnix   int64  `xorm:"updated"`
+}
+
+// TableName sets the database table name to be the correct one, as the
+// autogenerated table name for this struct is "o_auth2_grant".
+func (grant *OAuth2Grant) TableName() string {
+	return "oauth2_grant"
+}
+
+func AddScopeAndNonceColumnsToOAuth2Grant(x *xorm.Engine) error {
+	if err := x.Sync2(new(OAuth2Grant)); err != nil {
+		return fmt.Errorf("Sync2: %w", err)
+	}
+	return nil
+}