Chore 26 compare layer import export onnxruntime

Context

• [Add 🚀] necessary functions to easily create many unit-tests to try import/forward_dims/export of Aidge operators copying ONNX operators #26
  • function to create an ONNX model containing a single operator to test (any opset, any operator type).
    • create_op_graph() to create an ONNX model with a single operator and the right input shapes
    • infer_onnx_node_shape() to propagate dimensions to output Tensor if possible
  • Import the operator
    • update import function to copy input Tensor dimensions to Aidge model
  • Export the operator
    • update export function to copy input Tensor dimensions and run forward_dims() if necessary

Modified files

• unit_tests/utils.py
• unit_tests/test_relu.py first test to show what to compare and how to compare

Detailed major modifications

Add utils functions for ONNX graph generation and improve import/export functions.