Set memory order on slow atomics (#6920)

By default, the memory order on atomics is `seq_cst`. This is a relatively expensive ordering and it shows in situations where we're rapidly signaling a consumer to pick up something from a producer. I've instead attempted to switch these to `release` (producer) and `acquire` (consumer) to improve the performance of these signals. 

## Validation Steps Performed
- Run `time cat big.txt` and `time cat ls.txt` under VS Performance Profiler. 

## PR Checklist
* [x] Closes perf itch
* [x] I work here
* [x] Manual test
* [x] Documentation irrelevant.
* [x] Schema irrelevant.
* [x] Am core contributor.

.github/actions/spell-check/patterns/patterns.txt

@@ -19,3 +19,4 @@ TestUtils::VerifyExpectedString\(tb, L"[^"]+"
 Base64::s_(?:En|De)code\(L"[^"]+"
 VERIFY_ARE_EQUAL\(L"[^"]+"
 L"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789\+/"
+std::memory_order_[\w]+

src/cascadia/TerminalControl/ThrottledFunc.cpp

@@ -29,7 +29,7 @@ ThrottledFunc<>::ThrottledFunc(ThrottledFunc::Func func, TimeSpan delay, CoreDis
 // - <none>
 void ThrottledFunc<>::Run()
 {
-    if (_isRunPending.test_and_set())
+    if (_isRunPending.test_and_set(std::memory_order_acquire))
     {
         // already pending
         return;
@@ -44,7 +44,7 @@ void ThrottledFunc<>::Run()
                 if (auto self{ weakThis.lock() })
                 {
                     timer.Stop();
-                    self->_isRunPending.clear();
+                    self->_isRunPending.clear(std::memory_order_release);
                     self->_func();
                 }
             });

src/renderer/base/thread.cpp

@@ -162,17 +162,17 @@ DWORD WINAPI RenderThread::_ThreadProc()
     {
         WaitForSingleObject(_hPaintEnabledEvent, INFINITE);
 
-        if (!_fNextFrameRequested.exchange(false))
+        if (!_fNextFrameRequested.exchange(false, std::memory_order_acq_rel))
         {
             // <--
             // If `NotifyPaint` is called at this point, then it will not
             // set the event because `_fWaiting` is not `true` yet so we have
             // to check again below.
 
-            _fWaiting.store(true);
+            _fWaiting.store(true, std::memory_order_release);
 
             // check again now (see comment above)
-            if (!_fNextFrameRequested.exchange(false))
+            if (!_fNextFrameRequested.exchange(false, std::memory_order_acq_rel))
             {
                 // Wait until a next frame is requested.
                 WaitForSingleObject(_hEvent, INFINITE);
@@ -193,7 +193,7 @@ DWORD WINAPI RenderThread::_ThreadProc()
             // expensive operation, we should reset the event to not render
             // again if nothing changed.
 
-            _fWaiting.store(false);
+            _fWaiting.store(false, std::memory_order_release);
 
             // see comment above
             ResetEvent(_hEvent);
@@ -218,13 +218,13 @@ DWORD WINAPI RenderThread::_ThreadProc()
 
 void RenderThread::NotifyPaint()
 {
-    if (_fWaiting.load())
+    if (_fWaiting.load(std::memory_order_acquire))
     {
         SetEvent(_hEvent);
     }
     else
     {
-        _fNextFrameRequested.store(true);
+        _fNextFrameRequested.store(true, std::memory_order_release);
     }
 }