[ARROW-47590][C++]: Use explicit W functions in cpu_info.cc for UNICODE compatibility

- Replace GetModuleHandle with GetModuleHandleW
- Add L" prefix to string literals in cpu_info.cc
- Part of fixing Windows UNICODE build failure

Author: aLVINlEE9

cpp/src/arrow/util/cpu_info.cc

@@ -82,7 +82,7 @@ void OsRetrieveCacheSize(std::array<int64_t, kCacheLevels>* cache_sizes) {
   typedef BOOL(WINAPI * GetLogicalProcessorInformationFuncPointer)(void*, void*);
   GetLogicalProcessorInformationFuncPointer func_pointer =
       (GetLogicalProcessorInformationFuncPointer)GetProcAddress(
-          GetModuleHandle("kernel32"), "GetLogicalProcessorInformation");
+          GetModuleHandleW(L"kernel32"), "GetLogicalProcessorInformation");
 
   if (!func_pointer) {
     ARROW_LOG(WARNING) << "Failed to find procedure GetLogicalProcessorInformation";