Extract package formats into their own classes

Problem

In order to prepare the packages codebase for the possible future table decomposition we have to have a separate class for every package format.

Additionally, the package.rb contains the logic for all package formats and continue growing with every new package format and a new functionality. The complexity of maintainability grows simultaneously.

Solution

Extract every package format from Packages::Package model to its own model, e.g., Packages::Npm::Package, Packages::Maven::Package and update all related file like services, finders accordingly.