Replace all CRITICAL_SECTION usage with std::mutex and std::lock_guard

Migrates 59 files from WinAPI CRITICAL_SECTION to portable C++ std::mutex/std::lock_guard/std::unique_lock. Removes Linux CRITICAL_SECTION shims from winapi_stubs.h.

Minecraft.World/IO/Files/ConsoleSaveFileOriginal.cpp

@@ -777,11 +777,11 @@ int ConsoleSaveFileOriginal::getOriginalSaveVersion() {
 }
 
 void ConsoleSaveFileOriginal::LockSaveAccess() {
-    EnterCriticalSection(&m_lock);
+    m_lock.lock();
 }
 
 void ConsoleSaveFileOriginal::ReleaseSaveAccess() {
-    LeaveCriticalSection(&m_lock);
+    m_lock.unlock();
 }
 
 ESavePlatform ConsoleSaveFileOriginal::getSavePlatform() {