Incorrect Op*AccessChain instruction for vec ptr to scalar ptr casts

I was debugging an issue w/ vstore_local cl cts tests, which does something like:
```
vstore2( srcValues[ tid ], offsets[ tid ], ( (__local char *)sSharedStorage ) + alignmentOffset );
```

I've simplified this to a more trivial example:
```
__kernel void test_fn(__global int *res, __global int2 *v)
{
*res = ((__global int *)v)[1];
}
```
This generates an `AccessChain` instruction like:
```
%10 = OpFunctionParameter %_ptr_CrossWorkgroup_v2uint
%15 = OpInBoundsPtrAccessChain %_ptr_CrossWorkgroup_uint %10 %uint_0 %uint_1
```
I believe this should have been an `OpInBoundsAccessChain` instead, or equivalently:
```
%15 = OpInBoundsPtrAccessChain %_ptr_CrossWorkgroup_uint %10 %uint_0 %uint_0 %uint_1
```
given that for the Ptr access chain variants:
> The type of Base after being dereferenced with Element is still the same as the original type of Base.

Note also spirv-val doesn't seem to be checking the resulting type of the AccessChain instruction, since it doesn't seem to complain about this. Perhaps a separate bug?

(Originally filed at https://github.com/KhronosGroup/SPIRV-Tools/issues/1498 but that seems to be the wrong place)

Start with the simplified OpenCL reproducer and inspect the generated SPIR-V AccessChain instruction shown in the issue. Compare the emitted pointer access-chain form with the stated expected forms, and check how spirv-val handles the result. Done means the cast produces a valid, type-correct access chain for this case and the behavior is covered by an appropriate regression check.

Written by the indexing model from the issue text.