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>

tests/integration/org_team_invite_test.go

@@ -0,0 +1,72 @@
+// 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 integration
+
+import (
+	"fmt"
+	"net/http"
+	"testing"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/organization"
+	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/test"
+	"code.gitea.io/gitea/tests"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestOrgTeamEmailInvite(t *testing.T) {
+	if setting.MailService == nil {
+		t.Skip()
+		return
+	}
+
+	defer tests.PrepareTestEnv(t)()
+
+	org := unittest.AssertExistsAndLoadBean(t, &organization.Organization{ID: 3})
+	team := unittest.AssertExistsAndLoadBean(t, &organization.Team{ID: 2})
+	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 5})
+
+	isMember, err := organization.IsTeamMember(db.DefaultContext, team.OrgID, team.ID, user.ID)
+	assert.NoError(t, err)
+	assert.False(t, isMember)
+
+	session := loginUser(t, "user1")
+
+	url := fmt.Sprintf("/org/%s/teams/%s", org.Name, team.Name)
+	csrf := GetCSRF(t, session, url)
+	req := NewRequestWithValues(t, "POST", url+"/action/add", map[string]string{
+		"_csrf": csrf,
+		"uid":   "1",
+		"uname": user.Email,
+	})
+	resp := session.MakeRequest(t, req, http.StatusSeeOther)
+	req = NewRequest(t, "GET", test.RedirectURL(resp))
+	session.MakeRequest(t, req, http.StatusOK)
+
+	// get the invite token
+	invites, err := organization.GetInvitesByTeamID(db.DefaultContext, team.ID)
+	assert.NoError(t, err)
+	assert.Len(t, invites, 1)
+
+	session = loginUser(t, user.Name)
+
+	// join the team
+	url = fmt.Sprintf("/org/invite/%s", invites[0].Token)
+	csrf = GetCSRF(t, session, url)
+	req = NewRequestWithValues(t, "POST", url, map[string]string{
+		"_csrf": csrf,
+	})
+	resp = session.MakeRequest(t, req, http.StatusSeeOther)
+	req = NewRequest(t, "GET", test.RedirectURL(resp))
+	session.MakeRequest(t, req, http.StatusOK)
+
+	isMember, err = organization.IsTeamMember(db.DefaultContext, team.OrgID, team.ID, user.ID)
+	assert.NoError(t, err)
+	assert.True(t, isMember)
+}