Complete rewrite of Windows exec wrapper (#21510)

* supports pipelining for faster execution
* supports become (runas), creates interactive subsession under WinRM batch logon
* supports usage of arbitrary module_utils files
* modular exec wrapper payload supports easier extension
* integrates async wrapper behavior for pipelined/become'd async
* module_utils are loaded as true Powershell modules, no more runtime modifications to module code

lib/ansible/plugins/connection/__init__.py

@@ -61,6 +61,8 @@ class ConnectionBase(with_metaclass(ABCMeta, object)):
     '''
 
     has_pipelining = False
+    has_native_async = False # eg, winrm
+    always_pipeline_modules = False # eg, winrm
     become_methods = C.BECOME_METHODS
     # When running over this connection type, prefer modules written in a certain language
     # as discovered by the specified file extension.  An empty string as the