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.spvasm.expected.wgsl

@@ -0,0 +1,44 @@
+[[block]]
+struct buf0 {
+  zero : i32;
+};
+
+var<private> x_GLF_color : vec4<f32>;
+
+[[group(0), binding(0)]] var<uniform> x_5 : buf0;
+
+fn main_1() {
+  var x_9 : array<i32, 1>;
+  var x_10_phi : i32;
+  let x_33 : array<i32, 1> = x_9;
+  let x_6 : i32 = x_33[0u];
+  loop {
+    x_GLF_color = vec4<f32>(0.0, 0.0, 0.0, 0.0);
+    let x_7 : i32 = x_5.zero;
+    let x_8 : i32 = x_9[x_7];
+    if ((x_8 == x_6)) {
+      x_10_phi = 1;
+      break;
+    }
+    x_10_phi = 2;
+    break;
+  }
+  let x_10 : i32 = x_10_phi;
+  if (((x_10 == 1) || (x_10 == 2))) {
+    x_GLF_color = vec4<f32>(1.0, 0.0, 0.0, 1.0);
+  } else {
+    x_GLF_color = vec4<f32>(0.0, 0.0, 0.0, 0.0);
+  }
+  return;
+}
+
+struct main_out {
+  [[location(0)]]
+  x_GLF_color_1 : vec4<f32>;
+};
+
+[[stage(fragment)]]
+fn main() -> main_out {
+  main_1();
+  return main_out(x_GLF_color);
+}