utilities: Swapped to use std C++11 mutex/threading constructs

In theory, everything should now be C++11 compatible with respect to std::mutex/std::thread. This commit removes the cm_thread classes that are covered in C++11 standard while leaving the threading primitive constructions that are present in C++14/17 that are currently in use.

This MR should have no functional impact; but is useful in tracking the capabilities of all supported systems while also moving to use more of the standard. It also would be noteworthy if it causes any existing passing unit tests to fail since the previous semantics should have matched std::mutex and friends exactly.