add SPIR-V 1.4 testing for Image Operands and Loop Controls (#2034)

This PR adds targeted testing for SPIR-V 1.4 features. Specifically,
this PR adds testing for:

1. The new Image Operand for SignExtend and ZeroExtend.
2. The new Loop Controls MinIterations, MaxIterations,
IterationMultiple, PeelCount, and PartialCount.

test_conformance/spirv_new/CMakeLists.txt

@@ -27,6 +27,7 @@ set(${MODULE_NAME}_SOURCES
   test_op_vector_extract.cpp
   test_op_vector_insert.cpp
   test_op_vector_times_scalar.cpp
+  test_spirv_14.cpp
 )
 
 set(TEST_HARNESS_SOURCES