Dawn: Use DXC

Use DXC instead of FXC when available. This solves https://electronicarts.github.io/pbmpm/ not replaying correctly with D3D12 backend.

Author: Chainsawkitten

replay/Device.cpp

@@ -62,6 +62,7 @@ Device::Device(Adapter& adapter) {
     // Make sure debug labels are forwarded.
     std::vector<const char*> toggles;
     toggles.push_back("use_user_defined_labels_in_backend");
+    toggles.push_back("use_dxc");
 
     WGPUDawnTogglesDescriptor dawnToggles = {};
     dawnToggles.chain.sType = WGPUSType_DawnTogglesDescriptor;