Replace std::lock_guard and std::lock with std::scoped_lock (#1758)

std::scoped_lock was introduced in C++17 and is strictly better than
std::lock_guard as it supports locking any number of mutexes safely.
It's also easier to use than std::lock for locking multiple mutexes at
once.

hal/src/main/native/cpp/handles/HandlesInternal.cpp

@@ -17,7 +17,7 @@ static wpi::SmallVector<HandleBase*, 32>* globalHandles = nullptr;
 static wpi::mutex globalHandleMutex;
 HandleBase::HandleBase() {
   static wpi::SmallVector<HandleBase*, 32> gH;
-  std::lock_guard lock(globalHandleMutex);
+  std::scoped_lock lock(globalHandleMutex);
   if (!globalHandles) {
     globalHandles = &gH;
   }
@@ -30,7 +30,7 @@ HandleBase::HandleBase() {
   }
 }
 HandleBase::~HandleBase() {
-  std::lock_guard lock(globalHandleMutex);
+  std::scoped_lock lock(globalHandleMutex);
   auto index = std::find(globalHandles->begin(), globalHandles->end(), this);
   if (index != globalHandles->end()) {
     *index = nullptr;