[WebNN] Support RotaryEmbedding op (#23283)
WebNN doesn't provide a dedicated op for RotaryEmbedding. Instead, we
implement it by using a combination of WebNN ops. The decomposed graph
is referenced from DML EP at:
onnxruntime/core/providers/dml/DmlExecutionProvider/src/Operators/DmlOperatorRotaryEmbedding.cpp
