[WSLC] add WSLC CMake file in NuGet (#14543)

Add WSLC SDK Config.cmake file. Enable developers to consume the library with CMake.

Author: chemwolf6922

nuget/Microsoft.WSL.Containers/cmake/Microsoft.WSL.ContainersConfig.cmake

@@ -0,0 +1,57 @@
+if(TARGET Microsoft.WSL.Containers::SDK)
+    return()
+endif()
+
+if(NOT WIN32)
+    message(FATAL_ERROR "Microsoft.WSL.Containers: This package only supports Windows.")
+endif()
+
+# Determine target architecture
+if(CMAKE_GENERATOR_PLATFORM)
+    string(TOLOWER "${CMAKE_GENERATOR_PLATFORM}" _wslcsdk_platform)
+    if(_wslcsdk_platform STREQUAL "x64")
+        set(_wslcsdk_arch "x64")
+    elseif(_wslcsdk_platform STREQUAL "arm64")
+        set(_wslcsdk_arch "arm64")
+    else()
+        message(FATAL_ERROR
+            "Microsoft.WSL.Containers: Unsupported platform '${CMAKE_GENERATOR_PLATFORM}'."
+            " Supported: x64, ARM64.")
+    endif()
+    unset(_wslcsdk_platform)
+elseif(CMAKE_SYSTEM_PROCESSOR)
+    string(TOLOWER "${CMAKE_SYSTEM_PROCESSOR}" _wslcsdk_platform)
+    if(_wslcsdk_platform MATCHES "amd64|x86_64|x64")
+        set(_wslcsdk_arch "x64")
+    elseif(_wslcsdk_platform MATCHES "arm64|aarch64")
+        set(_wslcsdk_arch "arm64")
+    else()
+        message(FATAL_ERROR
+            "Microsoft.WSL.Containers: Unsupported architecture '${CMAKE_SYSTEM_PROCESSOR}'."
+            " Supported: x64, ARM64.")
+    endif()
+    unset(_wslcsdk_platform)
+else()
+    message(FATAL_ERROR
+        "Microsoft.WSL.Containers: Could not determine target architecture."
+        " Set CMAKE_GENERATOR_PLATFORM or CMAKE_SYSTEM_PROCESSOR.")
+endif()
+
+# Compute paths relative to package root (<root>/cmake/ -> <root>/)
+get_filename_component(_wslcsdk_root "${CMAKE_CURRENT_LIST_DIR}/.." ABSOLUTE)
+set(_wslcsdk_include_dir "${_wslcsdk_root}/include")
+set(_wslcsdk_lib_dir "${_wslcsdk_root}/runtimes/win-${_wslcsdk_arch}")
+
+# Create imported target
+add_library(Microsoft.WSL.Containers::SDK SHARED IMPORTED GLOBAL)
+set_target_properties(Microsoft.WSL.Containers::SDK PROPERTIES
+    INTERFACE_INCLUDE_DIRECTORIES "${_wslcsdk_include_dir}"
+    IMPORTED_IMPLIB "${_wslcsdk_lib_dir}/wslcsdk.lib"
+    IMPORTED_LOCATION "${_wslcsdk_lib_dir}/wslcsdk.dll"
+)
+
+# Clean up temporary variables
+unset(_wslcsdk_arch)
+unset(_wslcsdk_root)
+unset(_wslcsdk_include_dir)
+unset(_wslcsdk_lib_dir)