Migrate to use new Shader Model API

The currently used method, SetShaderModel has been deprecated in
favour of SetHLSLShaderModel. This CL migrates Dawn, so that the
deprecated method can be removed from upstream.

BUG=chromium:976798

Change-Id: Id1e655b77291179dd6e15f1a85c8664f07cf8396
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/8220
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>

src/fuzzers/DawnSPIRVCrossHLSLFastFuzzer.cpp

@@ -33,7 +33,7 @@ namespace {
 
             // Using the options that are used by Dawn, they appear in ShaderModuleD3D12.cpp
             options.SetFlipVertY(true);
-            options.SetShaderModel(51);
+            options.SetHLSLShaderModel(51);
             compiler.CompileSpvToHlsl(input.data(), input.size(), options);
         });