[SYCL] Implement `sycl_ext_oneapi_fp4` extension (#22437)
Specifications:
-
https://github.com/intel/llvm/blob/8c0c6254fee1347420da51eff0990d749b00ffc2/sycl/doc/extensions/proposed/sycl_ext_oneapi_fp4.asciidoc
-
https://github.com/intel/llvm/blob/9ddd4094e336e2807577448315bb6bfc1c0e6c2a/sycl/doc/design/spirv-extensions/SPV_INTEL_fp_conversions.asciidoc
(older version of the spec, because newer version is not yet implemented
in the SPIR-V translator)
---------
Signed-off-by: Dmitry Vodopyanov <dmitry.vodopyanov@intel.com>
