[NV TensorRT RTX EP] enable weight stripped engines with EP Context (#24869)
Enable NV TRT RTX EP engines to be weight stripped always when using EP
Context
We want to always use weight-stripped engines for EP Context to reduce
disk footprint on end-user system. With this, there are two ways to load
weights
1. provide weights via bytestream (recommended)
2. original `model.onnx` present in the same folder as the
`model_ctx.onnx`
```cpp
std::vector<char> model_bytes = ReadFileFromDisk("model.onnx");
// weight refitting using bytesteam
std::unordered_map<std::string, std::string> rtx_ep_options;
rtx_ep_options[onnxruntime::nv::provider_option_names::kONNXBytestream] = std::to_string(reinterpret_cast<size_t>(model_bytes.data()));
rtx_ep_options[onnxruntime::nv::provider_option_names::kONNXBytestreamSize] = std::to_string(model_bytes.size());
```