Use symbol file to export symbols in onnxruntime library on AIX platform as well (#28016)
On AIX platform , the exporting of symbols in libonnxruntime library is
handled through `onnxruntime_c_api.cc` and CMake itself. Because of
which it exports lot of symbols but misses out
`OrtSessionOptionsAppendExecutionProvider_CPU`.
This change is to make the symbol exports on AIX platform similar to how
it is done for other platforms.