Support SPV_KHR_vulkan_memory_model rev2

Support collapsed into one commit:
- Asm/Dis support for SPV_KHR_vulkan_memory_model
- Add Vulkan mem model image operands to switch
- Add TODO for source/validate_image.cpp
- val: Image operands NonPrivateTexelKHR, VolatileTexelKHR have no operands
  This is required for memory model tests to pass SPIR-V validation.
- Round trip tests: Test new flags on OpCopyMemory*