* Move get_all_subclasses out of sys_info as it is unrelated to system
information.
* get_all_subclasses now returns a set() instead of a list.
* Don't port get_platform to sys_info as it is deprecated. Code using
the common API should just use platform.system() directly.
* Rename load_platform_subclass() to get_platform_subclass and do not
instantiate the rturned class.
* Test the compat shims in module_utils/basic.py separately from the new
API in module_utils/common/sys_info.py and module_utils/common/_utils.py
* 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.
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
