This version just gets the relevant paths from PluginLoader and then
uses the existing imp.find_plugin() calls in the AnsiballZ code to load
the proper module_utils.
Modify PluginLoader to optionally omit subdirectories (module_utils
needs to operate on top level dirs, not on subdirs because it has
a hierarchical namespace whereas all other plugins use a flat
namespace).
Rename snippet* variables to module_utils*
Add a small number of unittests for recursive_finder
Add a larger number of integration tests to demonstrate that
module_utils is working.
Whitelist module-style shebang in test target library dirs
Prefix module_data variable with b_ to be clear that it holds bytes data
