Create unit-tests

Create a set of unit-tests for each class and function.

• BenchmarkScheme
  • construction
    • __init__()
    • from_dict()
    • from_json()
  • getter
    • sub-scheme / config
  • setter
    • sub-scheme / config
• measure_inference.py
  • measure_time_inference()
    • model format (aidge/onnx)
    • input number
    • extra param
  • compute_output()
    • model format (aidge/onnx)
    • input number
• FormatDescriptor
  • construction
    • __init__()
    • from_dict()
  • runtime check: is_valid_dict()
    • What can be None
    • What is required/optional
• TensorSpec
  • construction
    • __init__()
    • from_dict()
  • runtime check: is_valid_dict()
    • What can be None
    • What is required/optional
  • init_values()
• SingleOperationConfig
  • construction
    • __init__()
    • from_dict()
  • runtime check: is_valid_dict()
    • What can be None
    • What is required/optional
  • override_with()
    • emptyness
    • input completion
    • attributes completion
  • as_model()
• TreeStructure
  • __getitem__()
  • __setitem__()
  • __add__()
  • __iter__()
  • __len__()
  • __eq__()
  • branches_with_leaves()
  • _is_valid_label()
  • to_subtree()
  • filter()
• registration system
  • model generation
  • compute output
  • measure inference time