add SPIR-V 1.6 testing for Nontemporal Image Operand (#2249)

Adds a basic test for reading from and writing to an image with the
optional Nontemporal image operand.

test_conformance/spirv_new/CMakeLists.txt

@@ -30,6 +30,7 @@ set(${MODULE_NAME}_SOURCES
   test_op_vector_times_scalar.cpp
   test_spirv_14.cpp
   test_spirv_15.cpp
+  test_spirv_16.cpp
 )
 
 set(TEST_HARNESS_SOURCES