Migrate clients from namedtuples/attr datastructures to dataclassess

[imrehg]

As the API client is doing now, use the more up to date and Python built in dataclassess where needed.

Originally posted by @acroz in #197 (comment)

[shehab-as]

If this has not been picked up I can give it a go? Interested to familiarize myself with the codebase.

[imrehg]

@ShehabMMohamed I think that would be cool. It would be nice to finish up #197 and based on that do all the changes (and also adding the coverage for Apps)