Move VkYcbcrSamplerHelper to its own files

The intent is to reuse this helper to create a YCbCr GM.

Change-Id: I4d6af42745dbf845e28753bec670ad4a75c393b2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/295443
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index fd207c4..d263b51 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1420,8 +1420,12 @@
     }
 
     if (skia_use_vulkan) {
+      sources += [ "tools/gpu/vk/VkTestContext.h" ]
       sources += [ "tools/gpu/vk/VkTestContext.cpp" ]
+      sources += [ "tools/gpu/vk/VkTestUtils.h" ]
       sources += [ "tools/gpu/vk/VkTestUtils.cpp" ]
+      sources += [ "tools/gpu/vk/VkYcbcrSamplerHelper.h" ]
+      sources += [ "tools/gpu/vk/VkYcbcrSamplerHelper.cpp" ]
     }
     if (skia_use_metal) {
       sources += [ "tools/gpu/mtl/MtlTestContext.mm" ]