[VitisAI] use binary mode for context ep (#21474)

### Description
<!-- Describe your changes. -->
We found text format could caused error.


### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
Because the OS could change the string so we decided to save it as
binary file.

onnxruntime/core/providers/vitisai/vitisai_execution_provider.cc

@@ -100,7 +100,7 @@ void VitisAIExecutionProvider::FulfillEPContextEnablement(
   auto& ep_ctx_graph = p_ep_ctx_model_->MainGraph();
   if (!ep_ctx_embed_mode_) {
     auto ep_ctx_cache_path_str = GetEPContextCacheFileLocation(ep_ctx_model_file_loc_, model_path_str_);
-    std::ofstream ep_ctx_cache_ofs(ep_ctx_cache_path_str.c_str(), std::ios::trunc);
+    std::ofstream ep_ctx_cache_ofs(ep_ctx_cache_path_str.c_str(), std::ios::trunc | std::ios::binary);
     if (!ep_ctx_cache_ofs.is_open()) {
       ORT_THROW("Failed to open a file to write EP context cache: ", ep_ctx_cache_path_str.c_str());
     }
@@ -136,7 +136,7 @@ std::vector<std::unique_ptr<ComputeCapability>> VitisAIExecutionProvider::GetCap
       info_["cacheDir"] = cache_dir;
       info_["cacheKey"] = cache_key;
       LOGS_DEFAULT(VERBOSE) << "Trying getting compilation cache from " << PathToUTF8String(ep_ctx_model_file_loc_);
-      auto ep_ctx_payload = RetrieveEPContextCache(graph_viewer.GetGraph(), ep_ctx_model_file_loc_, false);
+      auto ep_ctx_payload = RetrieveEPContextCache(graph_viewer.GetGraph(), ep_ctx_model_file_loc_, true);
       restore_backend_compilation_cache(cache_dir, cache_key, ep_ctx_payload, graph_viewer.ModelPath().string());
     } else {
       if (fs::exists(ep_ctx_model_file_loc_) && fs::is_regular_file(ep_ctx_model_file_loc_) && ep_ctx_enabled_) {