Windows: Validate any user handle permissions for syscall callbacks

In the terminate case, if we don't return early then we will delete the
FEX thread object but the actual terminate call that follows will
fail, leaving the thread in a bad state.

Source/Windows/ARM64EC/Module.cpp

@@ -39,6 +39,7 @@ $end_info$
 #include "Common/Module.h"
 #include "Common/CRT/CRT.h"
 #include "Common/PortabilityInfo.h"
+#include "Common/Handle.h"
 #include "DummyHandlers.h"
 #include "BTInterface.h"
 #include "Windows/Common/SHMStats.h"
@@ -959,6 +960,10 @@ NTSTATUS ThreadInit() {
 }
 
 NTSTATUS ThreadTerm(HANDLE Thread, LONG ExitCode) {
+  if (!FEX::Windows::ValidateHandleAccess(Thread, THREAD_TERMINATE)) {
+    return STATUS_ACCESS_DENIED;
+  }
+
   THREAD_BASIC_INFORMATION Info;
   if (auto Err = NtQueryInformationThread(Thread, ThreadBasicInformation, &Info, sizeof(Info), nullptr); Err) {
     return Err;