Add missing operators for basic onnx model exporting

Context

While trying to export a hugging face onnx model to cpp, some operators were missing So in this merge request, I add a reshape operator as well as adding back the matmul operator (that was previously removed because of old api use) to the export_cpp module, to be able to correctly export a basic MLP onnx model to cpp. The onnx model can be found at: https://huggingface.co/EclipseAidge/mobilenet_v1

Modified files

• Added reshape.h, reshape.cpp and matching jinja kernel to add Operator reshape to export
• operator.py, to add reshape and matmul operator as well as refactor some duplicate code
• matmul.cpp, ,matmul.h, to adapt the operator to the new api interface

Detailed major modifications

Created a reshape operator for the export (Basic memcopy of the input buffer to the output buffer)

Adapted the matmul kernel and jinja for the new operator interface (inputs_dims -> in_dims for exemple) Then added back this matmul operator in the export

In operator.py refactor all the shared code for all the composed operator:

• setupConv2D for both Conv2D and PaddedConv2
• setupElemWiseOp for all the elemwise operators (Add, Sub, Mul, ...)
• setupPooling for all the pooling operators (Max, Avg, PaddedMax, ...)

TODO

• (ref discussion !31 (comment 3330814)) Refactor the reshape operator as a non op for the c++ side (as the reshape doesn't affect the buffer, only the forward dims of the buffer and those are already calculated with the scheduler in python)