feat: refactor var description

[vorel99]

This is my second refactoring pull request. First was #1302
My aim is to replace dictionaries with classes for easier feature developing.

• new dataclasses for series description and series description hashable
• add property for common propertyes from dict
• support old dict like syntax in those classes
• remove describe_counts and describe_generic (logic moved to classes VarDescription)

[vorel99]

missing spark refactoring (tbd)

[fabclmnt]

Hi @vorel99 ,

Thank you for your contribution!
I'll just ask a small change, we don't use the "refactor: ". Please ensure that you use "feat: " instead or any other naming and convention that we are using for the automatic calculation of the package versions.

In what concerns the proposed changes we will be analyzing and validating wether they fit the roadmap for the package.

[aquemy]

@vorel99 The PR looks great. Whenever you are ready, please, mark it as Ready for review such that we can start the CI/CD. I'll also do some local tests to ensure everything is fine.