Fix65

Context

Fix aidge_onnx#65 (closed)

Related to aidge_onnx!119 (merged)

Modified files

• Node::inputName(): Update logic on how inputName so that parent output name is used by default. Also return empty string if the input is optional with no parent to be complient with ONNX standard.
• Add relevant doc
• Update binding of inputName and outputName to be snake case compliant