[DataType] Complete python binding to map all dtype values

Context

Complete python binding to map all dtype values, i.e. from python aidge_core.dtype.[float32|float64|int64|...] Defined str(aidge_core.dtype) to return:"float32"|"float64"|"int64"|...

This makes str(aidge_core.dtype) equal to str(ndarray.dtype) for common scalar types.

Modified files

Modified pybind_Data.cpp:

• Add python enum values for all defined dtypes as per the table of dtype names (lower case of the dtype names).
• Add str() binding such that str(tensor.dtype()) return bare enumeration names, suitable for comparison with numpy dtype names.

Detailed major modifications

No major modification.

Actually now gives access to all aidge_ocre dtypes as the binding is automatically generated form the type names.

TODO

No todo forecasted.