Download protobuf dependency on ARM64 build host (#24847)

Windows on ARM support AMD64 emulation, so we can use win64 version of protoc.

Description
Compilation on ARM64 machine fails due to missing protoc dependency.

Motivation and Context
With this change we can compile onnxruntime on Windows on Arm devices without setting protobuf manually. CMake will download and setup protoc dependency.

Author: qc-tbhardwa

cmake/external/onnxruntime_external_deps.cmake

@@ -132,6 +132,9 @@ if(NOT ONNX_CUSTOM_PROTOC_EXECUTABLE AND NOT onnxruntime_USE_VCPKG)
       elseif(CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL "x86")
         onnxruntime_fetchcontent_declare(protoc_binary URL ${DEP_URL_protoc_win32} URL_HASH SHA1=${DEP_SHA1_protoc_win32} EXCLUDE_FROM_ALL)
         FetchContent_Populate(protoc_binary)
+      elseif(CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL "ARM64")
+        onnxruntime_fetchcontent_declare(protoc_binary URL ${DEP_URL_protoc_win64} URL_HASH SHA1=${DEP_SHA1_protoc_win64} EXCLUDE_FROM_ALL)
+        FetchContent_Populate(protoc_binary)
       endif()
 
       if(protoc_binary_SOURCE_DIR)