Fix an issue of spirv_type used in local variable definitions

We previously use createOp() in SPV builder to create type declaration.
However, all type declarations should be placed in const-type-variable
declaration section. And duplicated type defintions ought to be avoided.
We now make a method in SPV builder to perform this operation with a
more general solution: makeGenericType().

SPIRV/SpvBuilder.h

@@ -181,6 +181,7 @@ public:
     Id makeSamplerType();
     Id makeSampledImageType(Id imageType);
     Id makeCooperativeMatrixType(Id component, Id scope, Id rows, Id cols);
+    Id makeGenericType(spv::Op opcode, std::vector<spv::IdImmediate>& operands);
 
     // accelerationStructureNV type
     Id makeAccelerationStructureType();