Internally, when targeting x86 Android, these files fail to compile:

impeller/renderer/backend/vulkan/yuv_conversion_vk.cc:33:22: error: conditional expression is ambiguous; 'const impeller::vk::SamplerYcbcrConversion' can be converted to 'unsigned long long' and vice versa
  return conversion_ ? conversion_.get() : VK_NULL_HANDLE;
                     ^ ~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~
impeller/renderer/backend/vulkan/pipeline_vk.cc:360:25: error: conditional expression is ambiguous; 'vk::Sampler' can be converted to 'unsigned long long' and vice versa
      immutable_sampler ? immutable_sampler->GetSampler() : VK_NULL_HANDLE;
                        ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~

The cause is that internally, VULKAN_HPP_TYPESAFE_CONVERSION is set but not for the GN build here. Copying from the vulkan docs:

On 64-bit platforms Vulkan-Hpp supports implicit conversions between C++ Vulkan handles and C Vulkan handles. On 32-bit platforms all non-dispatchable handles are defined as uint64_t, thus preventing type-conversion checks at compile time which would catch assignments between incompatible handle types. Due to that Vulkan-Hpp does not enable implicit conversion for 32-bit platforms by default and it is recommended to use a static_cast for the conversion like this: VkImage = static_cast<VkImage>(cppImage) to prevent converting some arbitrary int to a handle or vice versa by accident. If you're developing your code on a 64-bit platform, but want compile your code for a 32-bit platform without adding the explicit casts you can define VULKAN_HPP_TYPESAFE_CONVERSION to 1 in your build system or before including vulkan.hpp. On 64-bit platforms this define is set to 1 by default and can be set to 0 to disable implicit conversions.

I'm not sure if doing the static_cast on the VK_NULL_HANDLE in this PR is right though. When targeting x86, this macro ends up being defined as 0LL. But at the same time, putting the cast on the other ternary branch (e.g. static_cast<vk::Sampler>(immutable_sampler->GetSampler())) doesn't resolve the error.

List which issues are fixed by this PR. You must list at least one issue.
b/328355475

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