Repository transfer has to be confirmed, if user can not create repo for new owner (#14792)

* make repo as "pending transfer" if on transfer start doer has no right to create repo in new destination

* if new pending transfer ocured, create UI & Mail notifications

models/org_test.go

@@ -635,3 +635,21 @@ func TestHasOrgVisibleTypePrivate(t *testing.T) {
 	assert.Equal(t, test2, false) // user not a part of org
 	assert.Equal(t, test3, false) // logged out user
 }
+
+func TestGetUsersWhoCanCreateOrgRepo(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	users, err := GetUsersWhoCanCreateOrgRepo(3)
+	assert.NoError(t, err)
+	assert.Len(t, users, 2)
+	var ids []int64
+	for i := range users {
+		ids = append(ids, users[i].ID)
+	}
+	assert.ElementsMatch(t, ids, []int64{2, 28})
+
+	users, err = GetUsersWhoCanCreateOrgRepo(7)
+	assert.NoError(t, err)
+	assert.Len(t, users, 1)
+	assert.EqualValues(t, 5, users[0].ID)
+}