This IntelDPCPP cmake module enables the Intel® oneAPI DPC++/C++ Compiler.
You may need to set your CXX or CMAKE_CXX_COMPILER string to "icx" and
 this module passes appropriate compiler flags to enable DPCPP compiler
 through icx binary.


Steps to enable DPCPP compiler:

(1) To be able to use this module, User's environment should be setup so that
    "icx" binary is locatable(i.e in search path)
(2) Please make sure to use cmake version of 3.20 or above. Please provide at
    the top in user's CMakeLists.txt before enabling the DPCPP compiler mode.

    Eg: cmake_minimum_required(VERSION 3.20.0)

(3) To enable the DPCPP compiler mode,  User needs to add following lines
    to the Project's CMakeLists.txt file.

   list(APPEND CMAKE_MODULE_PATH "<Directory of FindIntelDPCPP.cmake module>")
   find_package(IntelDPCPP REQUIRED)

(4) Set -DCMAKE_C_COMPILER/-DCMAKE_CXX_COMPILER to Intel's ICX compiler.
    The define CMAKE_C_COMPILER/CMAKE_CXX_COMPILER (or) env variables CC/CXX
    can be used to override the default system C/C++ compilers.
    The value to the define/env can be fully specified or, if detectable,
    just the binary name.

    Defines:
    Eg: Linux: cmake -DCMAKE_C_COMPILER=icx -DCMAKE_CXX_COMPILER=icpx
        Windows: -DCMAKE_C_COMPILER=icx -DCMAKE_CXX_COMPILER=icx

        (OR)
             cmake \
             -DCMAKE_C_COMPILER=/disk/user/custominstall/icx \
             -DCMAKE_CXX_COMPILER=/disk/user/custominstall/icpx

    Env:
    Alternatively, one can export CC and CXX to icx
    Eg:
        export CC=icx (or) setenv CC icx
        export CXX=icpx (or) setenv CXX icpx

(5) Run Cmake ( Eg: cmake <Path to CmakeList.txt>)
(6) Build app ( Eg: cmake --build .)

The module sets tests the DPCPP compiler, checks the required compiler macros.

This module updates

``CMAKE_CXX_FLAGS``
  Appends CMAKE_CXX_FLAGS with ``SYCL_FLAGS``

This will define the following variables:

``IntelDPCPP_FOUND``
  True if the system has the DPCPP library.
``SYCL_LANGUAGE_VERSION``
  The SYCL language spec version by Compiler.
``SYCL_INCLUDE_DIR``
  Include directories needed to use SYCL.
``SYCL_IMPLEMENTATION_ID``
  The SYCL compiler variant.
``SYCL_FLAGS``
  SYCL specific flags for the compiler.

Note: I will create few examples and update this doc.
