Python 3.8 collections compatibility fixes.

Includes a new pylint blacklist plugin to prevent regressions.

test/units/modules/conftest.py

@@ -2,12 +2,12 @@
 # GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
 
 import json
-from collections import MutableMapping
 
 import pytest
 
 from ansible.module_utils.six import string_types
 from ansible.module_utils._text import to_bytes
+from ansible.module_utils.common._collections_compat import MutableMapping
 
 
 @pytest.fixture

test/units/modules/web_infrastructure/test_jenkins_plugin.py

@@ -1,7 +1,7 @@
-import collections
 from io import BytesIO
 
 from ansible.modules.web_infrastructure.jenkins_plugin import JenkinsPlugin
+from ansible.module_utils.common._collections_compat import Mapping
 
 
 def pass_function(*args, **kwargs):
@@ -145,4 +145,4 @@ def test__get_json_data(mocker):
         "{url}".format(url=GITHUB_DATA['url']),
         'CSRF')
 
-    assert isinstance(json_data, collections.Mapping)
+    assert isinstance(json_data, Mapping)