Python - code reduction

[baywet]

follow up of #2388 and #2406. Abstractions needs to have a new base request builder class with the request adapter, url template and paths parameters properties. One (or more) base constructor needs to be added to handle validation and assignment of those parameters. Depending on the type system a Base Request Configruation or a request configuration class needs to be added with the headers and options properties, and if the covariance in the generic type system allows it, the query parameters property. Generation needs to be updated accordingly