Expose model inputs and outputs number in `AI.MODELGET`

[DvirDukhan]

As INPUTS and OUTPUTS are required only for TF models in the AI.MODELSET command, we want to allow investigate model's input and outputs:

• ONNX:

 size_t n_input_nodes;
 ort->SessionGetInputCount(session, &n_input_nodes);
 size_t n_output_nodes;
 ort->SessionGetOutputCount(session, &n_output_nodes);

• Torch - User defined

[nishantgeorge]

I think AI.MODELGET might be more appropriate since it already returns information about the model's inputs, and AI.INFO does not.