Add remaining copyright statements, add licenses sanity test (#5098)

* Add sanity test (currently fails).

* doc_fragments can also be non-GPLv3+.

* Replace 'Author:' by 'Copyright:' in some specific cases.

* Avoid matching string for license checkers.

* Reformulate not to throw license detection off.

* Add PSF copyright notice for plugins/module_utils/_mount.py.

* Add generic copyright notices.

* Update changelog fragment.

plugins/module_utils/_mount.py

@@ -2,6 +2,8 @@
 # This code is part of Ansible, but is an independent component.
 # This particular file snippet, and this file snippet only, is based on
 # Lib/posixpath.py of cpython
+#
+# Copyright (c) 2001-2022 Python Software Foundation.  All rights reserved.
 # It is licensed under the PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2
 # (See LICENSES/PSF-2.0.txt in this collection)
 # SPDX-License-Identifier: PSF-2.0

plugins/modules/monitoring/datadog/datadog_event.py

@@ -6,6 +6,7 @@
 #
 # This module is proudly sponsored by iGeolise (www.igeolise.com) and
 # Tiny Lab Productions (www.tinylabproductions.com).
+# Copyright (c) Ansible project
 # GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
 # SPDX-License-Identifier: GPL-3.0-or-later
 

plugins/modules/monitoring/icinga2_host.py

@@ -3,6 +3,7 @@
 
 # This module is proudly sponsored by CGI (www.cgi.com) and
 # KPN (www.kpn.com).
+# Copyright (c) Ansible project
 # GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
 # SPDX-License-Identifier: GPL-3.0-or-later
 

plugins/modules/net_tools/snmp_facts.py

@@ -2,6 +2,7 @@
 # -*- coding: utf-8 -*-
 
 # This file is part of Networklore's snmp library for Ansible
+# Copyright (c) Ansible project
 # GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
 # SPDX-License-Identifier: GPL-3.0-or-later