Replace std::mutex with DefaultUnnamedMutex to avoid named mutex exhaustion

[rgomez391]

This pull request introduces a custom mutex class, DefaultUnnamedMutex, to work around a platform STL defect where std::mutex default construction creates named mutexes — which have a low system-wide limit. The new class ensures mutexes are unnamed by default, preventing handle exhaustion under heavy concurrency. All std::mutex usages are replaced with DefaultUnnamedMutex throughout the codebase.

STL mutex workaround:

• Added a new DefaultUnnamedMutex class in pal.h to replace std::mutex and avoid named mutexes. (Include/httpClient/pal.h Include/httpClient/pal.hR498-R515)
• Updated all instances of std::mutex to use DefaultUnnamedMutex in key classes and structures, including:
  • NetworkState (Source/Global/NetworkState.h Source/Global/NetworkState.hL79-R79)
  • http_singleton::singleton_access (Source/Global/global.cpp Source/Global/global.cppL28-R32)
  • AsyncState (Source/Task/AsyncLib.cpp Source/Task/AsyncLib.cppL48-R48)
  • AtomicVector (Source/Task/AtomicVector.h Source/Task/AtomicVector.hL97-R97)
  • SubmitCallback, QueueWaitRegistry, TaskQueuePortImpl, TaskQueueImpl (Source/Task/TaskQueueImpl.h [1] [2] [3] [4]
  • ThreadPool_stl.cpp and WaitTimer_stl.cpp mutexes (Source/Task/ThreadPool_stl.cpp [1] Source/Task/WaitTimer_stl.cpp [2] [3]
  • WebSocket state mutex (Source/WebSocket/hcwebsocket.h Source/WebSocket/hcwebsocket.hL184-R184)

General codebase update for thread safety:

• Ensured that all lock guards and atomic operations now use DefaultUnnamedMutex for consistent behavior across platforms. [1] [2]

Header and dependency updates:

• Included <mutex> in pal.h to support the new mutex class. (Include/httpClient/pal.h Include/httpClient/pal.hR16)