Split basic units (#33510)

Split the one monolithic test for basic.py into several files

* Split test_basic.py along categories.
  This is preliminary to get a handle on things.  Eventually we may want
  to further split it so each file is only testing a single function.
* Cleanup unused imports from splitting test_basic.py
* Port atomic_move test to pytest.
  Working on getting rid of need to maintain procenv
* Split a test of symbolic_mode_to_octal to follow unittest best practices
  Each test should only invoke the function under test once
* Port test_argument_spec to pytest.
* Fix suboptions failure

lib/ansible/module_utils/basic.py

@@ -1923,7 +1923,7 @@ class AnsibleModule(object):
             wanted = v.get('type', None)
             if wanted == 'dict' or (wanted == 'list' and v.get('elements', '') == 'dict'):
                 spec = v.get('options', None)
-                if spec is None or not params[k]:
+                if spec is None or k not in params or params[k] is None:
                     continue
 
                 self._options_context.append(k)