Add team member invite by email (#20307)

Allows to add (not registered) team members by email.

related #5353

Invite by mail:

![grafik](https://user-images.githubusercontent.com/1666336/178154779-adcc547f-c0b7-4a2a-a131-4e41a3d9d3ad.png)

Pending invitations:

![grafik](https://user-images.githubusercontent.com/1666336/178154882-9d739bb8-2b04-46c1-a025-c1f4be26af98.png)

Email:

![grafik](https://user-images.githubusercontent.com/1666336/178164716-f2f90893-7ba6-4a5e-a3db-42538a660258.png)

Join form:

![grafik](https://user-images.githubusercontent.com/1666336/178154840-aaab983a-d922-4414-b01a-9b1a19c5cef7.png)

Co-authored-by: Jack Hay <jjphay@gmail.com>

models/migrations/migrations.go

@@ -417,6 +417,8 @@ var migrations = []Migration{
 	NewMigration("Conan and generic packages do not need to be semantically versioned", fixPackageSemverField),
 	// v227 -> v228
 	NewMigration("Create key/value table for system settings", createSystemSettingsTable),
+	// v228 -> v229
+	NewMigration("Add TeamInvite table", addTeamInviteTable),
 }
 
 // GetCurrentDBVersion returns the current db version

models/migrations/v228.go

@@ -0,0 +1,26 @@
+// 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 migrations
+
+import (
+	"code.gitea.io/gitea/modules/timeutil"
+
+	"xorm.io/xorm"
+)
+
+func addTeamInviteTable(x *xorm.Engine) error {
+	type TeamInvite struct {
+		ID          int64              `xorm:"pk autoincr"`
+		Token       string             `xorm:"UNIQUE(token) INDEX NOT NULL DEFAULT ''"`
+		InviterID   int64              `xorm:"NOT NULL DEFAULT 0"`
+		OrgID       int64              `xorm:"INDEX NOT NULL DEFAULT 0"`
+		TeamID      int64              `xorm:"UNIQUE(team_mail) INDEX NOT NULL DEFAULT 0"`
+		Email       string             `xorm:"UNIQUE(team_mail) NOT NULL DEFAULT ''"`
+		CreatedUnix timeutil.TimeStamp `xorm:"INDEX created"`
+		UpdatedUnix timeutil.TimeStamp `xorm:"INDEX updated"`
+	}
+
+	return x.Sync2(new(TeamInvite))
+}