Move unit test compat code out of lib/ansible/. (#46996)

* Move ansible.compat.tests to test/units/compat/.
* Fix unit test references to ansible.compat.tests.
* Move builtins compat to separate file.
* Fix classification of test/units/compat/ dir.

test/units/modules/monitoring/test_circonus_annotation.py

@@ -6,7 +6,7 @@ import re
 import uuid
 from urllib3.response import HTTPResponse
 
-from ansible.compat.tests.mock import patch
+from units.compat.mock import patch
 from ansible.module_utils import basic
 from ansible.module_utils._text import to_bytes
 from ansible.modules.monitoring import circonus_annotation

test/units/modules/monitoring/test_icinga2_feature.py

@@ -7,7 +7,7 @@
 
 from ansible.modules.monitoring import icinga2_feature
 from units.modules.utils import AnsibleExitJson, AnsibleFailJson, ModuleTestCase, set_module_args
-from ansible.compat.tests.mock import patch
+from units.compat.mock import patch
 from ansible.module_utils import basic
 
 

test/units/modules/monitoring/test_pagerduty.py

@@ -1,4 +1,4 @@
-from ansible.compat.tests import unittest
+from units.compat import unittest
 from ansible.modules.monitoring import pagerduty
 
 import json

test/units/modules/monitoring/test_pagerduty_alert.py

@@ -1,4 +1,4 @@
-from ansible.compat.tests import unittest
+from units.compat import unittest
 from ansible.modules.monitoring import pagerduty_alert
 
 from ansible.module_utils.six.moves.urllib.parse import urlparse, urlencode, urlunparse