Async: Use new [Non]PostedAsyncCont and callOriginalCb
This new hierarchy of classes gives us a central mechanism for
managing both reply-posting and lockSpec unlocking.
* callOriginalCb: Now uses a modern C++ variadic template design
enabling it to handle both direct calling and std::bind()
re-binding of an arbitrary number of arguments from the caller.
This enables us to mostly eliminate the repeated, bespoke
definitions of callOriginalCb littered throughout the codebase.
We've also propagated these changes throughout the codebase in
this patch.
hayodea
816a047920