[CANN] Add dump_om_model flag (#20075)
### Description
New flag of `dump_om_model` for **CANN EP**, which defaults to "True".
### Motivation and Context
When building an onnx model with CANN EP, the intermediate **OM(offline
model for Ascend NPU)** is automatically saved. There are some users
don't want to dump OM when resources are limited.
This PR will resovle this situation with `dump_om_model=False`
