d3d12: actually execute the pending commands before processing resize

This makes sure all the resources are in the expected state

Fix the D3D12 case in https://github.com/libsdl-org/SDL/issues/6376
(cherry-picked from commit df1bd07dee)

src/render/direct3d12/SDL_render_d3d12.c

@@ -1287,8 +1287,7 @@ D3D12_CreateWindowSizeDependentResources(SDL_Renderer * renderer)
     D3D12_CPU_DESCRIPTOR_HANDLE rtvDescriptor;
 
     /* Release resources in the current command list */
-    D3D_CALL(data->commandList, Close);
-    D3D12_ResetCommandList(data);
+    D3D12_IssueBatch(data);
     D3D_CALL(data->commandList, OMSetRenderTargets, 0, NULL, FALSE, NULL);
 
     /* Release render targets */