[hlsl-writer] Use entry point interface canonicalization transform

This replaces the entry point IO component of the HLSL sanitizing
transform, and completes support for the new entry point IO syntax.

Struct emission in the HLSL writer is updated to use the correct
attributes depending on the pipeline stage usage.

Fixed: tint:511
Change-Id: I6a30ed2182ee19b2f25262a30a83685ffcb5ef25
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/46521
Auto-Submit: James Price <jrprice@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: James Price <jrprice@google.com>

samples/main.cc

@@ -714,6 +714,8 @@ int main(int argc, const char** argv) {
 #endif  // TINT_BUILD_MSL_WRITER
 #if TINT_BUILD_HLSL_WRITER
     case Format::kHlsl:
+      transform_manager.append(
+          std::make_unique<tint::transform::CanonicalizeEntryPointIO>());
       transform_manager.append(std::make_unique<tint::transform::Hlsl>());
       break;
 #endif  // TINT_BUILD_HLSL_WRITER