Move organization related structs into sub package (#18518)

* Move organization related structs into sub package

* Fix test

* Fix lint

* Move more functions into sub packages

* Fix bug

* Fix test

* Update models/organization/team_repo.go

Co-authored-by: KN4CK3R <admin@oldschoolhack.me>

* Apply suggestions from code review

Co-authored-by: KN4CK3R <admin@oldschoolhack.me>

* Fix fmt

* Follow suggestion from @Gusted

* Fix test

* Fix test

* Fix bug

* Use ctx but db.DefaultContext on routers

* Fix bug

* Fix bug

* fix bug

* Update models/organization/team_user.go

* Fix bug

Co-authored-by: KN4CK3R <admin@oldschoolhack.me>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

models/organization/main_test.go

@@ -0,0 +1,24 @@
+// Copyright 2021 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 organization
+
+import (
+	"path/filepath"
+	"testing"
+
+	"code.gitea.io/gitea/models/unittest"
+)
+
+func TestMain(m *testing.M) {
+	unittest.MainTest(m, filepath.Join("..", ".."),
+		"user.yml",
+		"org_user.yml",
+		"team.yml",
+		"team_repo.yml",
+		"team_unit.yml",
+		"team_user.yml",
+		"repository.yml",
+	)
+}