Add github_app_access_token lookup plugin (#7761)

* Add github_app_access_token lookup plugin

* Fix a typo in short_description

* Remove unused MockOpenUrl

* Fix MockJWT to be used on jwt_instance instead

* Fix a bunch of pep8 and pylint issue

* Remove JWT from requirements, also default jwt_instance and jwk_from_pem so they can be mocked

* Update version added

Co-authored-by: Felix Fontein <felix@fontein.de>

* Update git reference in doc

Co-authored-by: Felix Fontein <felix@fontein.de>

* Update plugins/lookup/github_app_access_token.py

Co-authored-by: Felix Fontein <felix@fontein.de>

* Expose token expiry as a configurable option

* Update BOTMETA.yml

* Update documentation

* Update example with var, so it is more readable

Co-authored-by: Felix Fontein <felix@fontein.de>

* Apply suggestions from code review

Co-authored-by: Felix Fontein <felix@fontein.de>

---------

Co-authored-by: Felix Fontein <felix@fontein.de>

tests/unit/plugins/lookup/test_github_app_access_token.py

@@ -0,0 +1,52 @@
+# -*- coding: utf-8 -*-
+# Copyright (c) 2023, Poh Wei Sheng <weisheng-p@hotmail.sg>
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+import json
+
+from ansible_collections.community.general.tests.unit.compat import unittest
+from ansible_collections.community.general.tests.unit.compat.mock import (
+    patch,
+    MagicMock,
+    mock_open
+)
+from ansible.plugins.loader import lookup_loader
+
+
+class MockJWT(MagicMock):
+    def encode(self, payload, key, alg):
+        return 'Foobar'
+
+
+class MockResponse(MagicMock):
+    response_token = 'Bar'
+
+    def read(self):
+        return json.dumps({
+            "token": self.response_token,
+        }).encode('utf-8')
+
+
+class TestLookupModule(unittest.TestCase):
+
+    def test_get_token(self):
+        with patch.multiple("ansible_collections.community.general.plugins.lookup.github_app_access_token",
+                            open=mock_open(read_data="foo_bar"),
+                            open_url=MagicMock(return_value=MockResponse()),
+                            jwk_from_pem=MagicMock(return_value='private_key'),
+                            jwt_instance=MockJWT(),
+                            HAS_JWT=True):
+            lookup = lookup_loader.get('community.general.github_app_access_token')
+            self.assertListEqual(
+                [MockResponse.response_token],
+                lookup.run(
+                    [],
+                    key_path="key",
+                    app_id="app_id",
+                    installation_id="installation_id",
+                    token_expiry=600
+                )
+            )