Improve ONNX tests

Context

See #66 (closed)

Modified files

• test_converter_register.py
  • Add missing keys
  • Check that all export and import keys are tested
  • Check that converter functions have a type hint and that the signature is the expected one.
  • Update check for import and export register that add and remove is working.
• onnx_export Remove deprecated verbose option

Detailed major modifications

TODO

• Check that converter functions have a type hint and that the signature is the expected one.