Create PyPI package class

Proposal

Extract the pypi package format related code from Packages::Package to Packages::Pypi::Package and update all related files like services, finders accordingly.

flowchart TB;
    Packages::Package --> Packages::Pypi::Package

Solution

Create new Active Record model Packages::Pypi::Package and use it for every interaction with PyPi packages whether it's a service, finder or API endpoint.

Note: the usage of the feature flag is highly encouraged.