Track the cursor dirty flag in the correct buffer (#20095)

Failure to do so will result in every console API requiring a cursor
update stalling for 500ms because we sent the update to the wrong
buffer.

Closes #20092

src/host/outputStream.cpp

@@ -36,7 +36,7 @@ void ConhostInternalGetSet::UnknownSequence() noexcept
     // us from using a more conservative solution (e.g. always fetching the cursor position).
     if (gci.IsInVtIoMode())
     {
-        gci.GetActiveOutputBuffer().SetConptyCursorPositionMayBeWrong();
+        gci.GetActiveOutputBuffer().GetActiveBuffer().SetConptyCursorPositionMayBeWrong();
     }
 }
 

src/server/ApiDispatchers.cpp

@@ -595,9 +595,12 @@ constexpr T saturate(auto val)
     RETURN_IF_FAILED(pObjectHandle->GetScreenBuffer(GENERIC_READ, &pObj));
 
     // See ConptyCursorPositionMayBeWrong() for details.
-    if (pObj->ConptyCursorPositionMayBeWrong())
+    auto& activeBuffer = pObj->GetActiveBuffer();
+    // GetConsoleScreenBufferInfoExImpl uses GetActiveBuffer internally, but
+    // under the console lock.
+    if (activeBuffer.ConptyCursorPositionMayBeWrong())
     {
-        pObj->WaitForConptyCursorPositionToBeSynchronized();
+        activeBuffer.WaitForConptyCursorPositionToBeSynchronized();
     }
 
     m->_pApiRoutines->GetConsoleScreenBufferInfoExImpl(*pObj, ex);

src/terminal/adapter/InteractDispatch.cpp

@@ -166,7 +166,7 @@ void InteractDispatch::MoveCursor(const VTInt row, const VTInt col)
 
     // Unblock any callers inside SCREEN_INFORMATION::WaitForConptyCursorPositionToBeSynchronized().
     // The cursor position has now been updated to the terminal's.
-    info.ResetConptyCursorPositionMayBeWrong();
+    info.GetActiveBuffer().ResetConptyCursorPositionMayBeWrong();
 }
 
 // Routine Description: