Update migrated repositories' issues/comments/prs poster id if user has a github external user saved (#7751)

* update migrated issues/comments when login as github

* add get userid when migrating or login with github oauth2

* fix lint

* add migrations for repository service type

* fix build

* remove unnecessary dependencies on migrations

* add cron task to update migrations poster ids and fix posterid when migrating

* fix lint

* fix lint

* improve code

* fix lint

* improve code

* replace releases publish id to actual author id

* fix import

* fix bug

* fix lint

* fix rawdata definition

* fix some bugs

* fix error message

services/externalaccount/user.go

@@ -0,0 +1,66 @@
+// Copyright 2019 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 externalaccount
+
+import (
+	"strconv"
+	"strings"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/structs"
+
+	"github.com/markbates/goth"
+)
+
+// LinkAccountToUser link the gothUser to the user
+func LinkAccountToUser(user *models.User, gothUser goth.User) error {
+	loginSource, err := models.GetActiveOAuth2LoginSourceByName(gothUser.Provider)
+	if err != nil {
+		return err
+	}
+
+	externalLoginUser := &models.ExternalLoginUser{
+		ExternalID:        gothUser.UserID,
+		UserID:            user.ID,
+		LoginSourceID:     loginSource.ID,
+		RawData:           gothUser.RawData,
+		Provider:          gothUser.Provider,
+		Email:             gothUser.Email,
+		Name:              gothUser.Name,
+		FirstName:         gothUser.FirstName,
+		LastName:          gothUser.LastName,
+		NickName:          gothUser.NickName,
+		Description:       gothUser.Description,
+		AvatarURL:         gothUser.AvatarURL,
+		Location:          gothUser.Location,
+		AccessToken:       gothUser.AccessToken,
+		AccessTokenSecret: gothUser.AccessTokenSecret,
+		RefreshToken:      gothUser.RefreshToken,
+		ExpiresAt:         gothUser.ExpiresAt,
+	}
+
+	if err := models.LinkExternalToUser(user, externalLoginUser); err != nil {
+		return err
+	}
+
+	externalID, err := strconv.ParseInt(externalLoginUser.ExternalID, 10, 64)
+	if err != nil {
+		return err
+	}
+
+	var tp structs.GitServiceType
+	for _, s := range structs.SupportedFullGitService {
+		if strings.EqualFold(s.Name(), gothUser.Provider) {
+			tp = s
+			break
+		}
+	}
+
+	if tp.Name() != "" {
+		return models.UpdateMigrationsByType(tp, externalID, user.ID)
+	}
+
+	return nil
+}