Remove nsync (#20413)
### Description
1. Remove the onnxruntime::OrtMutex class and replace it with
~absl::Mutex~ std::mutex.
2. After this change, most source files will not include <Windows.h>
indirectly.
### Motivation and Context
To reduce the number of deps we have, and address some Github issues
that are related to build ONNX Runtime from source.
In PR #3000 , I added a custom implementation of std::mutex . It was
mainly because at that time std::mutex's default constructor was not
trivial on Windows. If you had such a mutex as a global var, it could
not be initialized at compile time. Then VC++ team fixed this issue.
Therefore we don't need this custom implementation anymore.
This PR also removes nsync. I ran several models tests on Linux. I
didn't see any perf difference.
This PR also reverts PR #21005 , which is no longer needed since conda
has updated its msvc runtime DLL.
This PR unblocks #22173 and resolves #22092 . We have a lot of open
issues with nsync. This PR can resolve all of them.
