ESIMD failures if the SYCL functor isn't decomposed

[Naghasan]

Describe the bug

Noticed while working on #18258. Some ESIMD tests fails if the functor isn't decomposed. The only difference in emitted code will be the usm pointer never goes through an address space cast to generic (it passed directly as a pointer to generic instead).

The patch implements a flags that forces the non decomposition of the functor, but the behaviour can also be highlighted by simply wrapping the kernel in a lambda.

Affected tests:

SYCL :: ESIMD/lsc/lsc_load_store_2d_smoke.cpp
SYCL :: ESIMD/unified_memory_api/scatter_usm.cpp
SYCL :: ESIMD/usm_gather_scatter_rgba.cpp
SYCL :: ESIMD/usm_gather_scatter_rgba_64.cpp
SYCL :: ESIMD/vadd_raw_send_gen12.cpp

To reproduce

If the patch wasn't merged, wrap the kernel in a lambda. For instance, extracting the base test of scatter_usm.cpp:

       auto kernel = [=](sycl::nd_item<1> ndi) SYCL_ESIMD_KERNEL {
         uint16_t GlobalID = ndi.get_global_id(0);
         simd<int32_t, NOffsets> ByteOffsets(GlobalID * N * sizeof(T),
                                             VS * sizeof(T));
         auto ByteOffsetsView = ByteOffsets.template select<NOffsets, 1>();
         simd<T, N> Vals = gather<T, N, VS>(Out, ByteOffsets);
         Vals *= 2;
         auto ValsView = Vals.template select<N, 1>();
         simd_mask<NOffsets> Pred = 0;
         for (int I = 0; I < NOffsets; I++) {
           Pred[I] = (I % MaskStride == 0) ? 1 : 0;
           if (GlobalID % 4 == 0)
             scatter(Out, ByteOffsets, Vals);
           else if (GlobalID % 4 == 1)
             scatter(Out, ByteOffsetsView, Vals);
           else if (GlobalID % 4 == 2)
             scatter<T, N>(Out, ByteOffsets, ValsView);
           else if (GlobalID % 4 == 3)
             scatter<T, N>(Out, ByteOffsetsView, ValsView);
         }
       };
       cgh.parallel_for(Range, [=](sycl::nd_item<1> ndi)
                                   SYCL_ESIMD_KERNEL { kernel(ndi); });

this force the parameter to be passed as <{ ptr addrspace(4), i32, [4 x i8] }>

Environment

• OS: [e.g Windows/Linux]
• Target device and vendor: [e.g. Intel GPU]
• DPC++ version: [e.g. commit hash or output of clang++ --version]
• Dependencies version: [e.g. the output of sycl-ls --verbose]

Additional context

No response