Move all mail related codes from models to services/mailer (#7200)

* move all mail related codes from models to modules/mailer

* fix lint

* use DBContext instead Engine

* use WithContext not WithEngine

* Use DBContext instead of Engine

* don't use defer when sess.Close()

* move DBContext to context.go and add some methods

* move mailer from modules/ to services

* fix lint

* fix tests

* fix fmt

* add gitea copyright

* fix tests

* don't expose db functions

* make code clear

* add DefaultDBContext

* fix build

* fix bug

routers/user/auth_openid.go

@@ -18,6 +18,7 @@ import (
 	"code.gitea.io/gitea/modules/recaptcha"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/timeutil"
+	"code.gitea.io/gitea/services/mailer"
 
 	"gitea.com/macaron/captcha"
 )
@@ -444,7 +445,8 @@ func RegisterOpenIDPost(ctx *context.Context, cpt *captcha.Captcha, form auth.Si
 
 	// Send confirmation email, no need for social account.
 	if setting.Service.RegisterEmailConfirm && u.ID > 1 {
-		models.SendActivateAccountMail(ctx.Context, u)
+		mailer.SendActivateAccountMail(ctx.Locale, u)
+
 		ctx.Data["IsSendRegisterMail"] = true
 		ctx.Data["Email"] = u.Email
 		ctx.Data["ActiveCodeLives"] = timeutil.MinutesToFriendly(setting.Service.ActiveCodeLives, ctx.Locale.Language())