[Feature Request] [Vulkan] Implement `vk::SampledTexture` type

[luciechoi]

This is an issue created for the implementation of vk::SampledTexture type, whose design was written and approved here.

• Implement the simplest type and methodvk::SampledTexture2D.Sample().
  • Allow default type parameter float4.
  • Allow optional arguments.
• Implement all other builtin methods
  • CalculateLevelOfDetail
  • CalculateLevelOfDetailUnclamped
  • Gather
  • GetDimensions
  • GetSamplePosition
  • Load
  • SampleBias
  • SampleCmp
  • SampleCmpLevelZero
  • SampleGrad
  • SampleLevel
  • mips[] operator
  • sample[] operator
• Implement for all other types
  • SampledTexture1D
  • SampledTexture1DArray
  • SampledTexture2DArray
  • SampledTexture2DMS
  • SampledTexture2DMSArray
  • SampledTexture3D
  • SampledTextureCUBE
  • SampledTextureCUBEArray
• Add hlsl_vk_sampled_texture feature check to the preprocessor
• Add tests to offload-test-suite.

[damyanp]

@luciechoi - proposal 34 is listed as "Under Review". If it's been approved, can you submit a PR that changes to state to "Accepted" please?