onnxruntime

12121aa1 - Update API ReadOpAttr and CreateOpAttr for string type to unblock EPs to process EPContext node for ep_cache_context with bytes stream (#25389)

Update API ReadOpAttr and CreateOpAttr for string type to unblock EPs to process EPContext node for ep_cache_context with bytes stream (#25389) The existing API ReadOpAttr & CreateOpAttr for string type always assume there '\0' at the end. It blocks the EPs to embed/read the context binary byte buffer into EPContext node ep_cache_context attribute. Update the customer op API ReadOpAttr for string type to avoid adding '\0' at the end. Update CreateOpAttr API to construct the string with len. Keep the strings type processing as it is for now.