message: Remove unused SwapChainImplVulkan
diff: namespace utils {
  - class SwapChainImplVulkan {
  - public:
  - using WSIContext = dawnWSIContextVulkan;
  -
  - SwapChainImplVulkan(GLFWwindow* /*window*/) {
  - }
  -
  - ~SwapChainImplVulkan() {
  - }
  -
  - void Init(dawnWSIContextVulkan*) {
  - }
  -
  - dawnSwapChainError Configure(dawnTextureFormat, dawnTextureUsageBit, uint32_t, uint32_t) {
  - return DAWN_SWAP_CHAIN_NO_ERROR;
  - }
  -
  - dawnSwapChainError GetNextTexture(dawnSwapChainNextTexture*) {
  - return DAWN_SWAP_CHAIN_NO_ERROR;
  - }
  -
  - dawnSwapChainError Present() {
  - return DAWN_SWAP_CHAIN_NO_ERROR;
  - }
  - };
  -
  class VulkanBinding : public BackendBinding {
  public:
  void SetupGLFWWindowHints() override {
  