move invite by mail to services package (#21513)

followup  #20307
close #21511

-> make it easy to also add API equivalent later ...

services/org/team_invite.go

@@ -0,0 +1,23 @@
+// 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 org
+
+import (
+	"context"
+
+	org_model "code.gitea.io/gitea/models/organization"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/services/mailer"
+)
+
+// CreateTeamInvite make a persistent invite in db and mail it
+func CreateTeamInvite(ctx context.Context, inviter *user_model.User, team *org_model.Team, uname string) error {
+	invite, err := org_model.CreateTeamInvite(ctx, inviter, team, uname)
+	if err != nil {
+		return err
+	}
+
+	return mailer.MailTeamInvite(ctx, inviter, team, invite)
+}