Deprecate TextureCopyView::arrayLayer -> origin.z

All existing tests and samples are updated and deprecation tests added.

CommandEncoder still encodes using arrayLayers so the backends are
unchanged. They will be handled in a follow-up CL.

Bug: dawn:22

Change-Id: Ib5346b46eb04d97349cab8f32ef8da5034726ca8
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/23104
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Jiawei Shao <jiawei.shao@intel.com>
Commit-Queue: Jiawei Shao <jiawei.shao@intel.com>

src/utils/WGPUHelpers.cpp

@@ -276,12 +276,10 @@ namespace utils {
 
     wgpu::TextureCopyView CreateTextureCopyView(wgpu::Texture texture,
                                                 uint32_t mipLevel,
-                                                uint32_t arrayLayer,
                                                 wgpu::Origin3D origin) {
         wgpu::TextureCopyView textureCopyView;
         textureCopyView.texture = texture;
         textureCopyView.mipLevel = mipLevel;
-        textureCopyView.arrayLayer = arrayLayer;
         textureCopyView.origin = origin;
 
         return textureCopyView;

src/utils/WGPUHelpers.h

@@ -53,7 +53,6 @@ namespace utils {
                                               uint32_t rowsPerImage);
     wgpu::TextureCopyView CreateTextureCopyView(wgpu::Texture texture,
                                                 uint32_t level,
-                                                uint32_t slice,
                                                 wgpu::Origin3D origin);
 
     struct ComboRenderPassDescriptor : public wgpu::RenderPassDescriptor {