Add touch tests for volatile atomics

Add touch tests for volatile atomics

Volatile atomics are a late addition to the SPV_KHR_vulkan_memory_model
extension. This change adds variants of the spirv_assembly opatomic tests
that use the bit to make sure it is accepted, but don't actually prove
that the access is treated as volatile.

SPIR-V issue: 476
Components: Vulkan
Affects: dEQP-VK.spirv_assembly.*atomic*

Change-Id: I38202242dade7dcf42aa2bbcd1927a1cac1bc9ad