Add support for SPIR-V extension: SPV_INTEL_function_pointers (#80759)

This PR adds initial support for "SPV_INTEL_function_pointers" SPIR-V
extension:
https://github.com/intel/llvm/blob/sycl/sycl/doc/design/spirv-extensions/SPV_INTEL_function_pointers.asciidoc

The goal of the extension is to support indirect function calls and
translation of function pointers into SPIR-V.