writer/hlsl: Don't wrap arrays in structures

FXC has trouble dealing with these.
This was originally added to handle returning arrays as structures.
HLSL supports typedefs, which is a much simpiler solution, and doesn't upset FXC.

Bug: tint:848
Bug: tint:904
Change-Id: Ie841c9c454461a885a35c41476fd4d05d3f34cbf
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/56774
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
diff --git a/test/expressions/zero_init/struct/array.wgsl.expected.hlsl b/test/expressions/zero_init/struct/array.wgsl.expected.hlsl
index c514b14..6b9d582 100644
--- a/test/expressions/zero_init/struct/array.wgsl.expected.hlsl
+++ b/test/expressions/zero_init/struct/array.wgsl.expected.hlsl
@@ -3,11 +3,8 @@
   return;
 }
 
-struct tint_array_wrapper {
-  float arr[4];
-};
 struct S {
-  tint_array_wrapper a;
+  float a[4];
 };
 
 void f() {