Make SpecImpl hashable

@olivierbichler made SpecImpl hashable we need to use this to put SpecsImpl in python set and dictionnary.

added Enhancement ⭐ label

assigned to @cmoineau

mentioned in merge request !163 (merged)

added to epic &12 (closed)

added StatusTODO label

removed StatusTODO label

added StatusTODO label

@olivierbichler after reflexion, this is not really an issue as it just force a suboptimal search for the ImplSpec. Creating a system to make ImplSpec hashable may even be counterproductive as we will introduce functions that may cause error in the future for minimal gain.

I close this issue for now.

closed