Add tests derived from VK-GL-CTS

This adds SPIR-V assembly and WGSL tests derived from VK-GL-CTS commit
571256871c2e2f03995373e1e4a02958d8cd8cf5. The following procedure was
followed:

- Those .amber files in VK-GL-CTS wholly owned by Google were
  identified

- All GLSL and SPIR-V shaders were extracted from the Amber files and
  converted into SPIR-V binaries

- The compact-ids pass of spirv-opt was applied to each binary

- Duplicate binaries were removed

- spirv-opt -O was used to obtain an optimized version of each remaining
  binary, with duplicates discarded

- Binaries that failed validation using spirv-val with target
  environment SPIR-V 1.3 were discarded

- Those binaries that tint could not successfully convert into WGSL were
  put aside for further investigation

- SPIR-V assembly versions of the remaining binaries are included in
  this CL

- test-runner with -generate-expected and -generate-skip was used to
  generate expected .spvasm, .msl, .hlsl and .wgsl outputs for these
  SPIR-V assembly tests

- Each successfully-generated .expected.wgsl is included in this CL
  again, as a WGLSL test

- test-runner with -generate-expected and -generate-skip was used again,
  to generate expected outputs for these WGSL tests

Change-Id: Ibe9baf2729cf97e0b633db9a426f53362a5de540
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/58842
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>

test/vk-gl-cts/graphicsfuzz/cov-reduce-load-array-replace-extract/0.wgsl.expected.msl

@@ -0,0 +1,49 @@
+#include <metal_stdlib>
+
+using namespace metal;
+struct buf0 {
+  /* 0x0000 */ int zero;
+};
+struct tint_array_wrapper {
+  int arr[1];
+};
+struct main_out {
+  float4 x_GLF_color_1;
+};
+struct tint_symbol_1 {
+  float4 x_GLF_color_1 [[color(0)]];
+};
+
+void main_1(constant buf0& x_5, thread float4* const tint_symbol_4) {
+  tint_array_wrapper x_9 = {};
+  int x_10_phi = 0;
+  tint_array_wrapper const x_33 = x_9;
+  int const x_6 = x_33.arr[0u];
+  while (true) {
+    *(tint_symbol_4) = float4(0.0f, 0.0f, 0.0f, 0.0f);
+    int const x_7 = x_5.zero;
+    int const x_8 = x_9.arr[x_7];
+    if ((x_8 == x_6)) {
+      x_10_phi = 1;
+      break;
+    }
+    x_10_phi = 2;
+    break;
+  }
+  int const x_10 = x_10_phi;
+  if (((x_10 == 1) || (x_10 == 2))) {
+    *(tint_symbol_4) = float4(1.0f, 0.0f, 0.0f, 1.0f);
+  } else {
+    *(tint_symbol_4) = float4(0.0f, 0.0f, 0.0f, 0.0f);
+  }
+  return;
+}
+
+fragment tint_symbol_1 tint_symbol(constant buf0& x_5 [[buffer(0)]]) {
+  thread float4 tint_symbol_5 = 0.0f;
+  main_1(x_5, &(tint_symbol_5));
+  main_out const tint_symbol_2 = {.x_GLF_color_1=tint_symbol_5};
+  tint_symbol_1 const tint_symbol_3 = {.x_GLF_color_1=tint_symbol_2.x_GLF_color_1};
+  return tint_symbol_3;
+}
+