Since moving to distro, it is possible to return this information for all platforms, not just Linux.
Also return version information for all platfrom not just Linux.
Update unit tests.
Remove some duplicate unit tests though I think there are more to remove.
* Fix docstring formatting
* Minor docstring changes
* Mock distro.id for Solaris service test
* Update comment
To avoid issues with Flatcar Container Linux being unable to be found,
detect Flatcar distro name especially for hostname, just like CoreOS
Container Linux was supported.
See also https://github.com/ansible/ansible/issues/69516
* 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
