tint->dawn: Shuffle source tree in preperation of merging repos

docs/    -> docs/tint/
fuzzers/ -> src/tint/fuzzers/
samples/ -> src/tint/cmd/
src/     -> src/tint/
test/    -> test/tint/

BUG=tint:1418,tint:1433

Change-Id: Id2aa79f989aef3245b80ef4aa37a27ff16cd700b
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/80482
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>

test/tint/expressions/zero_init/mat4x3/f32.wgsl

@@ -0,0 +1,3 @@
+fn f() {
+    var v = mat4x3<f32>();
+}

test/tint/expressions/zero_init/mat4x3/f32.wgsl.expected.glsl

@@ -0,0 +1,10 @@
+#version 310 es
+
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+void unused_entry_point() {
+  return;
+}
+void f() {
+  mat4x3 v = mat4x3(0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f);
+}
+

test/tint/expressions/zero_init/mat4x3/f32.wgsl.expected.hlsl

@@ -0,0 +1,8 @@
+[numthreads(1, 1, 1)]
+void unused_entry_point() {
+  return;
+}
+
+void f() {
+  float4x3 v = float4x3(0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f);
+}

test/tint/expressions/zero_init/mat4x3/f32.wgsl.expected.msl

@@ -0,0 +1,7 @@
+#include <metal_stdlib>
+
+using namespace metal;
+void f() {
+  float4x3 v = float4x3();
+}
+

test/tint/expressions/zero_init/mat4x3/f32.wgsl.expected.spvasm

@@ -0,0 +1,29 @@
+; SPIR-V
+; Version: 1.3
+; Generator: Google Tint Compiler; 0
+; Bound: 13
+; Schema: 0
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint GLCompute %unused_entry_point "unused_entry_point"
+               OpExecutionMode %unused_entry_point LocalSize 1 1 1
+               OpName %unused_entry_point "unused_entry_point"
+               OpName %f "f"
+               OpName %v "v"
+       %void = OpTypeVoid
+          %1 = OpTypeFunction %void
+      %float = OpTypeFloat 32
+    %v3float = OpTypeVector %float 3
+%mat4v3float = OpTypeMatrix %v3float 4
+         %10 = OpConstantNull %mat4v3float
+%_ptr_Function_mat4v3float = OpTypePointer Function %mat4v3float
+%unused_entry_point = OpFunction %void None %1
+          %4 = OpLabel
+               OpReturn
+               OpFunctionEnd
+          %f = OpFunction %void None %1
+          %6 = OpLabel
+          %v = OpVariable %_ptr_Function_mat4v3float Function %10
+               OpStore %v %10
+               OpReturn
+               OpFunctionEnd

test/tint/expressions/zero_init/mat4x3/f32.wgsl.expected.wgsl

@@ -0,0 +1,3 @@
+fn f() {
+  var v = mat4x3<f32>();
+}