[Add] Possibility to create a GenericOperator from any Operator

Context

One envisionned use-case is to be able to replace actual Operator obejcts with GenericOperator that would behave differently even regarding the size of inputs/outputs Tensors.

For example, a Conv that works on 4-bits packed data, which input/output size would be different from the standard Conv operator because of memory alignments. This would be useful for the export of sub 8-bits kernels in the Cortex-M export.

Major modifications

Add possibility to create a GenericOperator from any Operator.

• add: toGenericOp() recipe to convert operator into GenericOperator
• add: Operator::inputCategory() getter for input categories
• add: comparison operator= to DynamicAttributes
• add: GenericOperator constructor from Operator
• add: unit-tests for toGenericOperator() recipe
• upd: make std::array and std::pair recursively hashable in DynamicAttributes
• upd: make almost every StaticAttributes convertible to DynamicAttributes