onnxruntime

Accomodate BE platforms. Make sure we always write flatbuffers LE (#22375)

### Description
<!-- Describe your changes. -->
flatbuffers always write data in LE and it is automatically traslated
to/from BE as needed,
but only if we use proper accessors. This would work for shape.
However, we store parameters as bytes, so we need to swap bytes as
needed for BE.

### Motivation and Context
Address https://github.com/microsoft/onnxruntime/issues/22364