onnxruntime [WebNN] Handle in-memory external data

Description

Some initializers are stored as in-memory external data, WebNN EP should support these initializers.

Motivation and Context

This PR:

Added HasExternalDataInMemory check for external data to avoid unexpected error.
Wrapped the UnpackInitializerData to make it compatible with external data.

Fixed #25078

Jun 16 '25 09:06 Honry

@yuslepukhin, @fs-eire, @fdwr, PTAL, thanks!

Jun 16 '25 09:06 Honry

/azp run ONNX Runtime Web CI Pipeline,Windows GPU CI Pipeline,Linux Android Emulator QNN CI Pipeline,Windows GPU WebGPU CI Pipeline,Windows OpenVINO CI Pipeline

Jun 18 '25 00:06 fdwr

/azp run Linux CPU CI Pipeline,Linux CPU Minimal Build E2E CI Pipeline,Linux GPU CI Pipeline,Linux GPU TensorRT CI Pipeline,Linux OpenVINO CI Pipeline,Linux QNN CI Pipeline,MacOS CI Pipeline,Windows ARM64 QNN CI Pipeline,Windows CPU CI Pipeline

Jun 18 '25 00:06 fdwr

/azp run Windows GPU CUDA CI Pipeline,Windows GPU DML CI Pipeline,Windows GPU Doc Gen CI Pipeline,Win_TRT_Minimal_CUDA_Test_CI

Jun 18 '25 00:06 fdwr

/azp run Windows GPU TensorRT CI Pipeline,onnxruntime-binary-size-checks-ci-pipeline,orttraining-linux-ci-pipeline,orttraining-linux-gpu-ci-pipeline,orttraining-ortmodule-distributed,Windows x64 QNN CI Pipeline,Big Models

Jun 18 '25 00:06 fdwr

Azure Pipelines successfully started running 1 pipeline(s).

Jun 18 '25 00:06 azure-pipelines[bot]

/azp run Test Linux CUDA x64 Release,Test Linux TensorRT x64 Release,web_Debug / build_onnxruntime_web,web_Release / build_onnxruntime_web

Jun 18 '25 00:06 fdwr

Azure Pipelines successfully started running 2 pipeline(s).

Jun 18 '25 00:06 azure-pipelines[bot]

No pipelines are associated with this pull request.

Jun 18 '25 00:06 azure-pipelines[bot]

Azure Pipelines successfully started running 1 pipeline(s).

Jun 18 '25 00:06 azure-pipelines[bot]

Azure Pipelines successfully started running 2 pipeline(s).

Jun 18 '25 00:06 azure-pipelines[bot]

LGTM with the typos fixed.

Thanks, typos fixed.

Jun 18 '25 01:06 Honry

/azp run ONNX Runtime Web CI Pipeline,Windows GPU CI Pipeline,Linux Android Emulator QNN CI Pipeline,Windows GPU WebGPU CI Pipeline,Windows OpenVINO CI Pipeline

Jun 18 '25 22:06 fdwr

/azp run Linux CPU CI Pipeline,Linux CPU Minimal Build E2E CI Pipeline,Linux GPU CI Pipeline,Linux GPU TensorRT CI Pipeline,Linux OpenVINO CI Pipeline,Linux QNN CI Pipeline,MacOS CI Pipeline,Windows ARM64 QNN CI Pipeline,Windows CPU CI Pipeline

Jun 18 '25 22:06 fdwr

Azure Pipelines successfully started running 1 pipeline(s).