Constraints serialization

[rozyczko]

Details in the PARAMETER_DEPENDENCY_SERIALIZATION.md file.
The file is to be moved to the docs once they're actually present.

[henrikjacobsenfys]

So this is essentially bringing back the unique ID's as far as I understand? If this is needed to make serialization work, then it looks good to me.

[damskii9992]

Why do we need to be able to resolve dependencies specifically in an object hierarchy?
We can make all of this much simpler if we simply use the global map and always resolve all pending dependencies.

all_parameters = [param for param in global_map.vertices() if param isinstance DescriptorNumber && hasattr(param, '_pending_dependency_string')]

For my remaining comments I made another PR with my suggested changes. It is mostly integrating your code further with the observer pattern and getting rid of the unique_name fallback as I don't see any use of that.