[upd] Operators - use properties and named Dictionaries for inputs/outputs

Context

Improve the Python API by providing clean, property-based access to inputs and outputs of Operators that are Tensor-based, and allow name-based access via dictionaries similar to .attr.

Proposal

Use properties for input/output tensors:

op.inputs   # → List of input tensors
op.outputs  # → List of output tensors

Support name-based access via nested dictionaries:

op.i.weight   # Access input named "weight"
op.o.data0    # Access output named "data0"

op.i and op.o behave like read-only attribute-accessible dictionaries.

Follows the naming defined in the operator metadata that is not used for now except for documentation (e.g., inputs: ['data0', 'weight', 'bias'])