d3d11: implement Adaptor, Backend, etc

This CL also moves some comman code in d3d12::Adapter and
d3d11::Backend to d3d::Adapter and d3d::Backend, so it can be
shared with d3d11 backend.

Bug: dawn:1705
Change-Id: Ica3bf33232d3380b7d4799c77bf9b43a8374a66e
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/126220
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Peng Huang <penghuang@chromium.org>

include/dawn/native/D3DBackend.h

@@ -0,0 +1,33 @@
+// Copyright 2023 The Dawn Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef INCLUDE_DAWN_NATIVE_D3DBACKEND_H_
+#define INCLUDE_DAWN_NATIVE_D3DBACKEND_H_
+
+#include <dxgi1_4.h>
+#include <windows.h>
+#include <wrl/client.h>
+
+#include "dawn/native/DawnNative.h"
+
+namespace dawn::native::d3d {
+
+struct DAWN_NATIVE_EXPORT AdapterDiscoveryOptions : public AdapterDiscoveryOptionsBase {
+    AdapterDiscoveryOptions(WGPUBackendType type, Microsoft::WRL::ComPtr<IDXGIAdapter> adapter);
+    Microsoft::WRL::ComPtr<IDXGIAdapter> dxgiAdapter;
+};
+
+}  // namespace dawn::native::d3d
+
+#endif  // INCLUDE_DAWN_NATIVE_D3DBACKEND_H_