Adding MatMul operator

Context

While trying to export the ConvNeXt onnx model to cpp, we encountered several issues. we needed to add broadcasting support for the matmul operator.

• matmul.hpp add broadcasting for matmul;

• matmul_config.jinja, and matmul_forward.jinja to include for matmul operator;

  operator.py , register matmul operator;

• test_export.cpp, add unit tests;

Detailed major modifications

Add matmul broadcasting and unit tests.

TODO

Added matmul broadcasting for exporting ConvNeXt model with aidge_export_cpp;

• NOT DONE
• DONE
• TO DO